Periphytic diatoms from an oligotrophic lentic system, Piraquara I reservoir, Paraná state, Brazil

Diatomáceas perifíticas de um sistema lêntico oligotrófico, reservatório do Piraquara I, estado do Paraná, Brasil

Angela Maria da Silva-Lehmkuhl Priscila Izabel Tremarin Ilka Schincariol Vercellino Thelma A. Veiga Ludwig About the authors

Abstract:

Knowledge of biodiversity in oligotrophic aquatic ecosystems is fundamental to plan conservation strategies for protected areas. This study assessed the diatom diversity from an urban reservoir with oligotrophic conditions. The Piraquara I reservoir is located in an Environmental Protection Area and is responsible for the public supply of Curitiba city and the metropolitan region. Samples were collected seasonally between October 2007 and August 2008. Periphytic samples were obtained by removing the biofilm attached to Polygonum hydropiperoides stems and to glass slides. The taxonomic study resulted in the identification of 87 diatom taxa. The most representative genera regarding the species richness were Pinnularia (15 species) and Eunotia (14 species). Five species were registered for the first time in Brazil and seven in the State of Paraná. Taxonomic and ecological comments of the species registered are provided.

Keywords:
artificial substrate; diatom ecology; macrophytes; reservoirs

Resumo:

O conhecimento da biodiversidade em ecossistemas aquáticos oligotróficos é fundamental para planejar estratégias de conservação de áreas protegidas. Este estudo teve como objetivo conhecer a diversidade de diatomáceas em um reservatório urbano com condições oligotróficas. O reservatório do Piraquara I está inserido em uma Área de Proteção Ambiental em região de manancial e é responsável pelo abastecimento público de Curitiba e região metropolitana. Foram realizadas coletas estacionais entre os meses de outubro de 2007 e agosto de 2008. As amostras perifíticas foram obtidas pela remoção do biofilme aderido a caules de Polygonum hydropiperoides e de lâminas de vidro. O estudo taxonômico resultou na identificação de 87 táxons. Os gêneros mais representativos, considerando a riqueza de espécies, foram Pinnularia (15 espécies) e Eunotia (14 espécies). Cinco espécies de diatomáceas foram registradas pela primeira vez no Brasil e sete no estado do Paraná. Comentários taxonômicos e ecológicos também são apresentados para as espécies encontradas.

Palavras-chave:
substrato artificial; ecologia de diatomáceas; macrófitas; reservatório

Introduction

Diatoms are considered one of the most representative groups of microalgae due to the number of described species. Approximately 12,000 species of diatoms have been described hitherto (Guiry 2012GUIRY, M.D. 2012. How many species of algae are there? Journal of Phycology 48: 1057-1063. http://dx.doi.org/10.1111/j.1529-8817.2012.01222.x
http://dx.doi.org/10.1111/j.1529-8817.20...
) although the estimated number of species is thought to be at least 30,000 (Mann e Vanormeligen 2013MANN, D.G. & VANORMELIGEN, P. 2013. An inordinate fondness? The number, distributions, and origins of diatom species. The Journal of Eukaryotic Microbiology 60: 414-420. http://dx.doi.org/10.1111/jeu.12047
http://dx.doi.org/10.1111/jeu.12047...
). Diatoms are excellent bioindicators of water quality, being sensible to environmental pollution and a number of anthropogenic pressures, such as the increase in nutrient concentrations, acidification, land use, and the presence of toxic chemicals dissolved in water (Leskinen & Hällfors 1990LESKINEN, E. & HÄLLFORS, G. 1990. Community structure of epiphytic diatoms in relation to eutrophication on the Hanko Peninsula, south coast of Finland. In: Proceeding of the Thent International Diatom Symposium (H. Simola, ed.). Koeltz Scientific Books, Koenigstein, p. 323-333., Lowe & Pan 1996LOWE, R.L. & PAN, Y. 1996. Benthic algal communities as biological monitors. In: Algal ecology: freshwater benthic ecosystems (R.J. Stevenson, M.L. Bothwell & R.L. Lowe, eds). Academic Press, New York, p. 705-739., Lobo et al. 2002LOBO, E.A., CALLEGARO, V.L.M. & BENDER, E.P. 2002. Utilização de algas diatomáceas epilíticas como indicadores da qualidade da água em rios e arroios da região hidrográfica do Guaíba, RS, Brasil. EDUNISC, Santa Cruz do Sul, 127p., Rimet et al. 2015RIMET, F., BOUCHEZ, A. & MONTUELLE, B. 2015. Benthic diatoms and phytoplankton to assess nutrient in large lakes: complementarity of their use in Lake Geneva (France-Switzerland). Ecol. Indic. 53: 231-239. http://dx.doi.org/10.1016/j.ecolind.2015.02.008
http://dx.doi.org/10.1016/j.ecolind.2015...
).

Diatoms release mucilage through raphe, rimoportulae and apical pore fields, facilitating the frustule adhesion to different types of substrates. This strategy contributes to diatoms representativeness in the periphytic community (Round et al. 1990ROUND, F.E., CRAWFORD, R.M. & MANN, D.G. 1990. The diatoms. Biology and morphology of the genera. New York, Cambridge University Press, p.129., Lowe 1996LOWE, R.L. 1996. Periphyton patterns in lakes. In: Algal ecology: freshwater benthic ecosystems (R.J. Stevenson, M.L. Bothwell & R.L. Lowe, eds). Academic Press, New York, p. 57-76.). The species composition of periphytic assemblages can be influenced by the substrate micro-topography (Murdock and Dodds 2007MURDOCK, J.N. & DODDS, W.K. 2007. Linking benthic algal biomass to stream substratum topography. Journal of Phycological 43: 449-460. http://dx.doi.org/10.1111/j.1529-8817.2007.00357.x
http://dx.doi.org/10.1111/j.1529-8817.20...
, Souza & Ferragut 2012SOUZA, M.L. & FERRAGUT, C. 2012. Influence of substratum surface roughness on periphytic algal community structure in a shallow tropical reservoir. Acta Limnol. Bras. 24(4): 397-407. http://dx.doi.org/10.1590/S2179-975X2013005000004
http://dx.doi.org/10.1590/S2179-975X2013...
). Inventories using substrates with different surface types usually hold a great algal diversity (Ács et al. 2000ÁCS, E., KISS, K.T., SZABÓ, K. & MAKK, J. 2000. Short-term colonization sequence of Periphyton on glass slides in a large river (River Danube, near Budapest). Algological Studies 100: 135-156.). Therefore, diatom inventories should be carried out in a great number of different environments and using diverse substrates to maximize the recovery of new species, extend the distribution of known species and better define their ecological preferences, which increase the reliability of environmental diagnostics.

Man-made lentic environments with oligotrophic conditions are rare in urban areas and are examples of environmental health. Unfortunately, human activities in the surrounding watershed have been accelerating the processes of eutrophication, affecting the water quality and the biodiversity, leading to the loss of important ecological functions (Tundisi 2003TUNDISI, J.G. 2003. Água no século XXI: enfrentando a escassez. RiMa: São Carlos - SP, p. 1-248., Torrisi et al. 2010TORRISI, M., SCURI, S., DELL´UOMO, A. & COCCHIONI, M. 2010. Comparative monitoring by means of diatoms, macroinvertebrates and chemical parameters of an Apennine watercourse of central Italy: The river Tenna. Ecol. Indic., 10: 910-913. http://dx.doi.org/10.1016/j.ecolind.2010.01.010
http://dx.doi.org/10.1016/j.ecolind.2010...
). Due to the undesirable impact of these activities on the water physical and chemical conditions, efforts have been generally focused on studying eutrophic environments rather than on preserving oligotrophic water bodies. For this reason, there is usually a gap in the knowledge of the algal diversity of protected areas, which creates exceptional opportunities to study the remaining oligotrophic environments (Kociolek & Stoermer 2009KOCIOLEK, J.P. & STOERMER, E.F. 2009. Oligotrophy: the forgotten end of an ecological spectrum. Acta Bot. Croat. 68: 465-472.).

Recent studies in oligotrophic Brazilian reservoirs contributed to the description of new diatom species in the genera Kurtkrammeria and Encyonema (Marquardt et al. 2016MARQUARDT, G.C., WENGRAT, S., BICUDO, D.C., WETZEL, C.E., ECTOR, L. & BICUDO, C.E.M. 2017. Morphology and distribution of Encyonema angustecapitatum Krammer species complex (Bacillariophyceae) with description of four new species from São Paulo, southeast Brazil. Fottea 17(2): 164-177. http://dx.doi.org/10.5507/fot.2017.008
http://dx.doi.org/10.5507/fot.2017.008...
, Marquardt et al. 2017MARQUARDT, G.C., BICUDO, C.E.M., LUDWIG, T.A.V., ECTOR, L. & WETZEL, C.E. 2018. Diatom assemblages (Bacillariophyta)in six tropical reservoirs from southeast Brazil: species composition and spatial and temporal variation patterns. Acta Limnologica Brasiliensia 30: e201. https://doi.org/10.1590/S2179-975X6417
https://doi.org/10.1590/S2179-975X6417...
) and extended the geographic distribution of the already known species (Canani et al. 2011CANANI, L.G.C., MENEZES, M. & TORGAN, L.C. 2011. Diatomáceas epilíticas de águas oligotróficas e ácidas do Sudeste do Brasil. Acta Bot. Bras. 25(1): 130-140. http://dx.doi.org/10.1590/S0102-33062011000100016
http://dx.doi.org/10.1590/S0102-33062011...
). Paleolimnological studies with diatoms are important in providing a further understanding of biodiversity, detecting the response of the assemblages over time. Generally, a decrease in the diatom diversity during the eutrophication process can be observed when comparing environments that were oligotrophic but are currently eutrophised (Faustino et al. 2016FAUSTINO, S.B., FONTANA, L., BARTOZEK, E.C.R., BICUDO, C.E.M. & BICUDO, D.C. 2016. Composition and distribution of diatom assemblages from core and surface sediments of a water supply reservoir in Southeastern Brazil. Biota Neotropica: 16(2): e20150129. http://dx.doi.org/10.1590/1676-0611-BN-2015-0129
http://dx.doi.org/10.1590/1676-0611-BN-2...
, Wengrat et al. 2017WENGRAT, S., PADIAL, A.A., JEPPESEN, E., DAVIDSON, T.A., FONTANA, L., COSTA-BÖDDEKER & BICUDO, D.C. 2017. Paleolimnological records reveal a biotic homogenization driven by eutrophication in tropical reservoirs. J. Paleolimnol https://doi.org/10.1007/s10933-017-9997-4
https://doi.org/10.1007/s10933-017-9997-...
).

Previous diatom inventories were carried out in urban reservoirs of the Iguaçu river basin along a trophic gradient ranging from mesotrophic (Passaúna, Bertolli et al. 2010BERTOLLI, L.M., TREMARIN, P.I. & LUDWIG, T.A.V. 2010. Diatomáceas perifíticas em Polygonum hydropiperoides Michaux, reservatório do Passaúna, Região Metropolitana de Curitiba, Paraná, Brasil. Acta Bot. Bras. 24(4):1065-1081. http://dx.doi.org/10.1590/S0102-33062010000400022
http://dx.doi.org/10.1590/S0102-33062010...
and Piraquara II, Marra et al. 2016MARRA, R.C., TREMARIN, P.I., ALGARTE, V.M. & LUDWIG, T.A. 2016. Epiphytic diatoms (Diatomeae) from Piraquara II urban reservoir, Paraná state. Biotaneotropica 16(4): e20160200. http://dx.doi.org/10.1590/1676-0611-BN-2016-0200
http://dx.doi.org/10.1590/1676-0611-BN-2...
), eutrophic (Iraí, Silva et al. 2010SILVA, A.M., TREMARIN, P.I., LUDWIG, T.A.V. & VERCELLINO, I.S. 2010. Diatomáceas perifíticas em um sistema eutrófico brasileiro (Reservatório do Iraí, estado do Paraná). Acta Botanica Brasilica . 24(4): 997-1016. http://dx.doi.org/10.1590/S0102-33062010000400015
http://dx.doi.org/10.1590/S0102-33062010...
) to hypereutrophic (Itaqui, Faria et al. 2010FARIA, D.M., TREMARIN, P.I. & LUDWIG, T.A.V. 2010. Diatomáceas perifíticas da represa Itaqui, São José dos Pinhais, Paraná: Fragilariales, Eunotiales, Achnanthales, e Gomphonema Ehrenberg. Biota Neotropica 10(3): http://www.biotaneotropica.org.br/v10n3/pt/abstract?inventory+bn04110032010
http://www.biotaneotropica.org.br/v10n3/...
). The Piraquara I reservoir, which was surveyed in the present study, is connected to Piraquara II reservoir. The macrophyte Polygonum hydropiperoides Michaux and glass slides were used as substrates to assess the periphytic diatoms in these reservoirs.

The present study aimed at assessing the composition of periphytic diatom assemblages from the oligotrophic reservoir Piraquara I. We provided measures, illustrations, taxonomical comments and ecological data based on scientific literature, in order to contribute to the knowledge of Brazilian diatoms from oligotrophic environments.

Material and Methods

The Piraquara I Reservoir (25º30'24.16'' S, 49º1'29.4'' W) is a man-made public water supply of the Iguaçu River basin located in an Environmental Protection Area which is in a transition zone between the dense and mixed ombrophilous forest. The Cayuguava river was dammed to construct the reservoir in 1979 (Figure 1) (Guimarães 2008GUIMARÃES, L.J.R. 2008. Levantamento das áreas potenciais ao assoreamento da barragem Piraquara I. Dissertação de Mestrado, Universidade Federal do Paraná Curitiba.). The reservoir has a 3.3 km2 of flooded area, 7 meters in depth, a flow rate of 600 l/s, and a water residence time of 438 days (Júnior et al. 2005JÚLIO JÚNIOR, H. F., THOMAZ, S. M., AOSTINHO, A. A., LATINI, J. D. 2005. Distribuição e caracterização dos reservatórios. In: RODRIGUES, L., THOMAZ, S. M., AGOSTINHO, A. A. & GOMES, L. C. (Eds). Biocenoses em reservatórios: padrões espaciais e temporais. São Carlos: Rima. cap. 1. p. 1-16.).

Figure 1
Sampling site in Piraquara I reservoir, Paraná state, Brazil. Artificial Substrate (AS) and Natural Substrate (NS). (shapefile map from SUDERHSA 2007SUDERHSA, 2007. http://www.aguasparana.pr.gov.br/modules/conteudo/conteudo.php?conteudo=80 (Acessed 06 September 2017).
http://www.aguasparana.pr.gov.br/modules...
).

The physical and chemical data were provided by the Paraná Environmental Institute (IAP) (unpublished data) and by the water company of Paraná State (SANEPAR) (unpublished data). The Trophic State Index (TSI) was calculated according to Lamparelli (2004)LAMPARELLI, M.C. 2004. Grau de trofia em corpos d'água do estado de São Paulo: avaliação dos métodos de monitoramento. Tese de doutorado, Universidade de São Paulo, São Paulo. (Zorzal-Almeida et al. 2017ZORZAL-ALMEIDA, S., BICUDO, D.C., LAMPARELLI, M.C., FERRAGUT, C. & BICUDO, C.E.M. 2017. Avaliação do índice de estado trófico e sua aplicação na represa Guarapiranga em longa série temporal. In: 100 Anos da represa Guarapiranga: lições e desafios (Bicudo, C.E.M. & Bicudo, D.C., eds). Editora CRV, Curitiba-PR, Brasil. p. 401-428.).

Samplings were carried out seasonally (i.e. in spring, summer, autumn, and winter) from October 2007 to August 2008, at two sampling stations. Periphytic samples were obtained from natural and artificial substrates. As natural substrates, we used stems of the macrophyte Polygonum hydropiperoides Michaux that were collected near the reservoir margin. The periphyton was obtained by scraping the stems with a razor blade wrapped in foil. Glass slides (7.5 cm x 2.5 cm) were used as artificial and inert substrates fixed to woody frames that were left submerged in the water column for 30 days. The artificial substrates were placed at about 80 meters far from the margin of the reservoir to prevent being eventually trapped in the macrophytes by the wind action.

Substrate fragments were fixed in Transeau's solution (6:3:1) (Bicudo & Menezes 2017BICUDO, C.E.M. & MENEZES, M. 2017. Gêneros de algas de águas continentais do Brasil (Chave de identificação e descrições). 3 ed. Rima, São Carlos.). The samples were treated by oxidation according to the method of Simonsen (1974)SIMONSEN, R. 1974. The diatom plankton of the Indian Ocean Expedition of R/V "Meteor", 1964-65 Meteor. Forschungsergebnisse Reihe D-Biologie. 19: 1-66. modified by Moreira-Filho & Valente-Moreira (1981)MOREIRA-FILHO, H. & VALENTE MOREIRA, I.M. 1981. Avaliação taxonômica e ecológica das diatomáceas (Bacillariophyceae) epífitas em algas pluricelulares obtidas nos litorais dos Estados do Paraná, Santa Catarina e São Paulo. Bol. Mus. Bot. Mun. 47: 1-17.. The material was air-dried onto glass slides and mounted in Naphrax® resin. Observations, measurements, and diatom photomicrographs were performed at 1000× magnification in an Olympus BX40 microscope equipped with a DP71 Olympus camera. Diatom identification was performed up to the lowest level of taxonomic hierarchy based on recent and classic literature (e.g. Lange-Bertalot 1993LANGE-BERTALOT, H. 1993. 85 Neue Taxa und über 100 weitere neu definierte Taxa ergänzend zur Süsswasserflora von Mitteleuropa. Bibliotheca Diatomologica 27: 1-164., 1999LANGE-BERTALOT, H. 1999. Neue Kombinationen von Taxa aus Achnanthes Bory (sensu lato). In Iconogr. Diatomol., Annotated Diatom Monographs (H. Lange-Bertalot, ed.). Gantner Verlag KG, Ruggell, 6:276-289., 2001LANGE-BERTALOT, H. 2001. Navicula sensu stricto. 10 Genera separated from Navicula sensu lato. Frustulia. Diatoms of Europe: diatoms of the European inland waters and comparable habitats. Ruggell: A.R.G. Gantner Verlag. K.G. 2:1-526., Lange-Bertalot & Metzeltin 1996LANGE-BERTALOT, H. & METZELTIN, D. 1996. Indicators of oligotrophy-800 taxa representative of three ecologically distinct lake types, Carbonate buffered-Oligodystrophic-Weakly buffered soft water. In Iconogr. Diatomol. (H. Lange-Bertalot, ed.). Gantner Verlag KG, Ruggell, 2:1-390., Metzeltin & Lange-Bertalot 1998METZELTIN, D. & LANGE-BERTALOT, H. 1998. Tropical diatoms of South America I. About 700 predominantly rarely known or new taxa representative of the neotropical flora. In Iconogr. Diatomol. (H. Lange-Bertalot , ed.) 5: 1-695., 2002METZELTIN, D. & LANGE-BERTALOT, H. 2002. Diatoms from the "Island Continent" Madagascar. In Iconogr. Diatomol (H. Lange-Bertalot, ed.). Gantner Verlag KG, Ruggell, 11: 1-286., 2005METZELTIN, D. & LANGE-BERTALOT, H. 2005. Diatoms of Uruguay. Compared with other taxa from South America and elsewhere. In Iconogr.Diatomol (H. Lange-Bertalot , ed.). Gantner Verlag KG, Ruggell, 15:1-736., 2007METZELTIN, D. & LANGE-BERTALOT, H. 2007. Tropical Diatoms of South America II. Special remarks on biogeographic disjunction. In Iconogr.Diatomol (H. Lange-Bertalot , ed.). Gantner Verlag KG, Ruggell, 18:1-877., Bahls 2015BAHLS, L.L. 2015. Kurtkrammeria, a new genus of freshwater diatoms (Bacillariophyta, Cymbellaceae) separated from Encyonopsis. Nova Hedwigia 101: 165-190. http://dx.doi.org/10.1127/nova_hedwigia/2015/0263
http://dx.doi.org/10.1127/nova_hedwigia/...
). For each taxon, we included information on morphometry, remarks on the autoecology (when available in literature) as well as on the occurrence in the samples (see also table 2). Taxonomic comments were provided only for poorly known species in Brazil. We considered that a species is recorded for the first time in Brazil and in the state of Paraná if it was not previously recorded in a published article. The studied materials were deposited at the herbarium of the State University of Paraná (UPCB) under the numbers 63371 to 63374 (glass slides) and 63375 to 63378 (macrophyte P. hydropiperoides).

Table 1
Physical and chemical characteristics of the Piraquara I reservoir registered seasonally between October 2007 and August 2008.
Table 2
Diatom species and seasonal occurrence on artificial and natural substrates in Piraquara I reservoir.

Results and Discussion

The Piraquara I reservoir was classified as oligotrophic by the TSI index, characterized by low concentrations of phosphorus and nitrogen, high transparency of the water column (up to 3.2 meters), and a slightly acid to nearly neutral pH. Summer showed the highest values of temperature and accumulated rainfall occurred in the summer sample (27ºC and 326.9 mm, respectively). The physical and chemical water parameters are shown in Table 1.

We identified 88 infrageneric taxa that belong to 35 genera. Pinnularia Ehrenberg (15 spp.) and Eunotia Ehrenberg (14 spp.) were the most representative diatoms in both substrates. The macrophyte P. hydropiperoides showed the highest richness (77) and the highest number of exclusive species (35) that represented 45.4% of the total substrate richness, whereas the artificial substrate presented 52 species and 10 exclusive taxa, which corresponded to 19.2% of the total substrate richness.

The species first recorded in Brazil were Achnanthidium neomicrocephalum Lange-Bertalot & Staab, Craticula riparia var. mollenhaurei Lange-Bertalot, Frustulia australocrassinervia Casa, Mataloni & Van de Vijver, Gomphonema spiculoides Gandhi and Stauroneis neohyalina Lange-Bertalot & Krammer. Seven diatoms are recorded for the first time in Paraná State: Craticula acidoclinata Lange-Bertalot & Metzeltin, Fragilaria billingsii Wengrat, Wetzel & Morales, Eunotia longicamelus Costa, Bicudo & Wetzel, Eunotia pseudoimplicata Lange-Bertalot, Costa & Wetzel, Humidophila biscutella (Moser, Lange-Bertalot & Mezeltin) Lowe, Kociolek, Johansen, Van de Vijver, Lange-Bertalot & Kopalová, Nitzschia semirobusta Lange-Bertalot and Pinnularia viridiformis var. minor Krammer.

Pinnularia and Eunotia (15 and 14 species, respectively) presented a higher species richness in Piraquara I reservoir. The presence of these genera was favored by the slight acidity, low conductivity and water oligotrophy conditions of the studied reservoir (Round et al. 1990ROUND, F.E., CRAWFORD, R.M. & MANN, D.G. 1990. The diatoms. Biology and morphology of the genera. New York, Cambridge University Press, p.129., Metzeltin & Lange-Bertalot 1998METZELTIN, D. & LANGE-BERTALOT, H. 1998. Tropical diatoms of South America I. About 700 predominantly rarely known or new taxa representative of the neotropical flora. In Iconogr. Diatomol. (H. Lange-Bertalot , ed.) 5: 1-695., Spaulding & Edlund 2009SPAULDING, S. & EDLUND, M. 2009. Pinnularia. In Diatoms of the United States. Retrieved November 20, 2017, from http://westerndiatoms.colorado.edu/taxa/genus/Pinnularia
http://westerndiatoms.colorado.edu/taxa/...
, Costa et al. 2017COSTA, L.F., WETZEL, C.E., LANGE-BERTALOT, H., ECTOR, L. & BICUDO, D.C. 2017. Taxonomy and ecology of Eunotia species (Bacillariophyta) in southeastern Brazilian reservoirs. Biblioth. Diatomol. 64: 1-302.). Eunotia was also the most representative genus in a eutrophic reservoir (Silva et al. 2010SILVA, A.M., TREMARIN, P.I., LUDWIG, T.A.V. & VERCELLINO, I.S. 2010. Diatomáceas perifíticas em um sistema eutrófico brasileiro (Reservatório do Iraí, estado do Paraná). Acta Botanica Brasilica . 24(4): 997-1016. http://dx.doi.org/10.1590/S0102-33062010000400015
http://dx.doi.org/10.1590/S0102-33062010...
) located near to the Piraquara I. However, only three Eunotia species (E. naegelii, E. minor and E. subarcuatoides), which have a wide tolerance to trophic gradients (Van Dam et al. 1994VAN DAM, H., MERTENS, A. & SINKELDAM, J. 1994. A coded checklist and ecological indicator values of freshwater diatoms from the Netherlands. Neth. J. Aquatic Ecol. 28(1): 117-133. http://dx.doi.org/10.1007/BF02334251
http://dx.doi.org/10.1007/BF02334251...
, Silva et al. 2010SILVA, A.M., TREMARIN, P.I., LUDWIG, T.A.V. & VERCELLINO, I.S. 2010. Diatomáceas perifíticas em um sistema eutrófico brasileiro (Reservatório do Iraí, estado do Paraná). Acta Botanica Brasilica . 24(4): 997-1016. http://dx.doi.org/10.1590/S0102-33062010000400015
http://dx.doi.org/10.1590/S0102-33062010...
, Costa et al. 2017COSTA, L.F., WETZEL, C.E., LANGE-BERTALOT, H., ECTOR, L. & BICUDO, D.C. 2017. Taxonomy and ecology of Eunotia species (Bacillariophyta) in southeastern Brazilian reservoirs. Biblioth. Diatomol. 64: 1-302.) and they are able to occur under oligotrophic and eutrophic conditions, were common to both reservoirs.

The genera Navicula, Gomphonema, and Nitzschia, which are commonly registered in nutrient-rich environments (Goldsborough & Robinson 1996GOLDSBOROUGH, L.G. & ROBINSON, G.C.C. 1996. Pattern in wetlands. In: Algal ecology: freshwater benthic ecosystems (R.J. Stevenson , M.L. Bothwell & R.L. Lowe, eds). Academic Press, New York, p. 77-117.), showed a high species number in both substrates at the mesotrophic and hypereutrophic reservoirs located nearby to Piraquara I (Bertolii et al. 2010BERTOLLI, L.M., TREMARIN, P.I. & LUDWIG, T.A.V. 2010. Diatomáceas perifíticas em Polygonum hydropiperoides Michaux, reservatório do Passaúna, Região Metropolitana de Curitiba, Paraná, Brasil. Acta Bot. Bras. 24(4):1065-1081. http://dx.doi.org/10.1590/S0102-33062010000400022
http://dx.doi.org/10.1590/S0102-33062010...
, Faria et al. 2010FARIA, D.M., TREMARIN, P.I. & LUDWIG, T.A.V. 2010. Diatomáceas perifíticas da represa Itaqui, São José dos Pinhais, Paraná: Fragilariales, Eunotiales, Achnanthales, e Gomphonema Ehrenberg. Biota Neotropica 10(3): http://www.biotaneotropica.org.br/v10n3/pt/abstract?inventory+bn04110032010
http://www.biotaneotropica.org.br/v10n3/...
, Marra et al. 2016MARRA, R.C., TREMARIN, P.I., ALGARTE, V.M. & LUDWIG, T.A. 2016. Epiphytic diatoms (Diatomeae) from Piraquara II urban reservoir, Paraná state. Biotaneotropica 16(4): e20160200. http://dx.doi.org/10.1590/1676-0611-BN-2016-0200
http://dx.doi.org/10.1590/1676-0611-BN-2...
).

The richest assemblage was obtained from Polygonum hydropiperoides (natural substrate), 77 species, and can be explained by the glabrous or pubescent petiole of this macrophyte (Melo 2008MELO, E.F. 2008. Flora da Serra do Cipó, Minas Gerais: Polygonaceae. Bol. Bot. Univ. São Paulo. 26(2): 165-174. http://dx.doi.org/10.11606/issn.2316-9052.v26i2p165-174
http://dx.doi.org/10.11606/issn.2316-905...
), which offers a greater architectural complexity than the smooth and uniform surface of glass slides. The roughness difference between substrates usually does not contribute to an increase in algal biomass, but it is an important factor in selecting the species composition of the periphyton (Burkholder 1996BURKHOLDER, J.M. 1996. Interactions of benthic algae with their substrata. In Algal ecology: freshwater benthic ecosystems (R.J. Stevenson, M.L. Bothwell & R.L. Lowe, eds). Academic Press, San Diego, p. 253-297., Souza & Ferragut 2012SOUZA, M.L. & FERRAGUT, C. 2012. Influence of substratum surface roughness on periphytic algal community structure in a shallow tropical reservoir. Acta Limnol. Bras. 24(4): 397-407. http://dx.doi.org/10.1590/S2179-975X2013005000004
http://dx.doi.org/10.1590/S2179-975X2013...
).

The diatom species richness found in the oligotrophic Piraquara I reservoir was lower than in the mesotrophic reservoirs Piraquara II and Passaúna (135 and 106 taxa, respectively), the eutrophic reservoir Iraí (96 taxa) and the hypereutrophic reservoir Itaqui (124 taxa) (Bertolli et al. 2010BERTOLLI, L.M., TREMARIN, P.I. & LUDWIG, T.A.V. 2010. Diatomáceas perifíticas em Polygonum hydropiperoides Michaux, reservatório do Passaúna, Região Metropolitana de Curitiba, Paraná, Brasil. Acta Bot. Bras. 24(4):1065-1081. http://dx.doi.org/10.1590/S0102-33062010000400022
http://dx.doi.org/10.1590/S0102-33062010...
, Silva et al. 2010SILVA, A.M., TREMARIN, P.I., LUDWIG, T.A.V. & VERCELLINO, I.S. 2010. Diatomáceas perifíticas em um sistema eutrófico brasileiro (Reservatório do Iraí, estado do Paraná). Acta Botanica Brasilica . 24(4): 997-1016. http://dx.doi.org/10.1590/S0102-33062010000400015
http://dx.doi.org/10.1590/S0102-33062010...
, Faria 2010FARIA, D.M., TREMARIN, P.I. & LUDWIG, T.A.V. 2010. Diatomáceas perifíticas da represa Itaqui, São José dos Pinhais, Paraná: Fragilariales, Eunotiales, Achnanthales, e Gomphonema Ehrenberg. Biota Neotropica 10(3): http://www.biotaneotropica.org.br/v10n3/pt/abstract?inventory+bn04110032010
http://www.biotaneotropica.org.br/v10n3/...
, Marra et al. 2016MARRA, R.C., TREMARIN, P.I., ALGARTE, V.M. & LUDWIG, T.A. 2016. Epiphytic diatoms (Diatomeae) from Piraquara II urban reservoir, Paraná state. Biotaneotropica 16(4): e20160200. http://dx.doi.org/10.1590/1676-0611-BN-2016-0200
http://dx.doi.org/10.1590/1676-0611-BN-2...
). The Piraquara II is a mesotrophic reservoir located downstream from Piraquara I. Both reservoirs shared the presence of 31 diatom species, of which 11 were recorded from oligotrophic to mesotrophic environments and 20 species had a wide trophic tolerance. The diatom assemblage had more species that are tolerant in Piraquara II than in Piraquara I. Although eutrophication might lead to a loss in diatom diversity (Wengrat et al. 2017WENGRAT, S., PADIAL, A.A., JEPPESEN, E., DAVIDSON, T.A., FONTANA, L., COSTA-BÖDDEKER & BICUDO, D.C. 2017. Paleolimnological records reveal a biotic homogenization driven by eutrophication in tropical reservoirs. J. Paleolimnol https://doi.org/10.1007/s10933-017-9997-4
https://doi.org/10.1007/s10933-017-9997-...
), the species richness in shallow lakes might be also influenced by the presence, abundance and diversity of macrophytes (Sayer et al. 1999SAYER, C.D, ROBERTS, N., SADLER, J., DAVID, C. & WADE, P.M. 1999. Biodiversity changes in a shallow lake ecosystem: a multi-proxy palaeolimnological analysis. Journal of Biogeography 26(1): 97-114. http://dx.doi.org/10.1111/j.1365-2699.1999.00298.x
http://dx.doi.org/10.1111/j.1365-2699.19...
, Bicudo et al. 2007BICUDO, D.C., FONSECA, B.M., BINI, L.M., CROSSETI, L.O., BICUDO, C.E.M. & ARAÚJO-JESUS, T. 2007. Undesirable side-effects of water hyacinth control in a shallow tropical reservoir. Freshwater Biology 52: 1120-1133. http://dx.doi.org/10.1111/j.1365-2427.2007.01738.x
http://dx.doi.org/10.1111/j.1365-2427.20...
). Piraquara II and Itaqui had more diatom richness than the other reservoirs, which can be related to the fact that in the former reservoir were sampled three different species of macrophytes (Marra et al. 2016MARRA, R.C., TREMARIN, P.I., ALGARTE, V.M. & LUDWIG, T.A. 2016. Epiphytic diatoms (Diatomeae) from Piraquara II urban reservoir, Paraná state. Biotaneotropica 16(4): e20160200. http://dx.doi.org/10.1590/1676-0611-BN-2016-0200
http://dx.doi.org/10.1590/1676-0611-BN-2...
), and that the latter reservoir was almost totally covered by the floating macrophyte Pistia stratiotes L. (Faria et al. 2010FARIA, D.M., TREMARIN, P.I. & LUDWIG, T.A.V. 2010. Diatomáceas perifíticas da represa Itaqui, São José dos Pinhais, Paraná: Fragilariales, Eunotiales, Achnanthales, e Gomphonema Ehrenberg. Biota Neotropica 10(3): http://www.biotaneotropica.org.br/v10n3/pt/abstract?inventory+bn04110032010
http://www.biotaneotropica.org.br/v10n3/...
, Faria et al. 2013FARIA, D.M., GUIMARÃES, A.T.B. & LUDWIG, T.A.V. 2013. Responses of periphytic diatoms to mechanical removal to Pistia stratiotes L. in a hypereutrophic subtropical reservoir: dynammic and tolerance. Brazilian Journal of Biology 73(4): 681-689. http://dx.doi.org//10.1590/S1519-69842013000400002
http://dx.doi.org//10.1590/S1519-6984201...
).

Summer showed the highest accumulated rainfall (326.9 mm) during the sampling period and the lowest species number in both substrates. High rainfall lead to the detachment of the periphyton from the substrates (Casartelli et al. 2016CASARTELLI, M.R., LAVAGNOLLI, G.J. & FERRAGUT, C. 2016. Periphyton biomass accrual rate changes over the colonization process in a shallow mesotrophic reservoir. Acta Limnologica Brasiliensia 28: e9. http://dx.doi.org/10.1590/S2179-975X0116
http://dx.doi.org/10.1590/S2179-975X0116...
), which certainly contributed to the less number of species registered in Piraquara I. We registered nine diatom species (Spicaticribra kingstonii, Eunotia intermedia, Eunotia parasiolii, Eunotia pseudoimplicata, Encyonopsis subminuta, Cymbopleura naviculiformis, Planothidium incuriatum, Capartogramma crucicula and Nitzschia nana) that occurred in spring on both substrates, but were not recorded in summer. These species release mucilage and remain attached to the substrates and are therefore commonly observed from the periphytic samples (Round et al. 1990ROUND, F.E., CRAWFORD, R.M. & MANN, D.G. 1990. The diatoms. Biology and morphology of the genera. New York, Cambridge University Press, p.129., Santos et al. 2011SANTOS, E.M., TREMARIN, P.I. & LUDWIG, T.A.V. 2011. Diatomáceas perifíticas em Potamogeton polygonus Cham. & Schltdl.: citações pioneiras para o estado do Paraná. Biota Neotropica 11(3): http://www.biotaneotropica.org.br/v11n3/pt/abstract?inventory+bn01611032011
http://www.biotaneotropica.org.br/v11n3/...
, Montoya-Moreno et al. 2011MONTOYA-MORENO, Y., SALA, S., VOUILLOUD, A. & AGUIRRE, N. 2011. Capartogramma crucicula (Grunow ex Cleve) Ross, primer registro del género para Colombia. Universitas Scientiarum 16(1): 70-76.). In summer, we registered temporary losses of species that were retrieved again during the sampling period. As shown in Table 2, the planktonic and benthic diatoms registered were Aulacoseira ambigua, Cyclotella meneghiniana, Fragilaria recapitellata, Fragilaria sp., Ulnaria delicatissima, Eunotia intricans, Eunotia paratridentula, Encyonopsis schubartii, Achnanthidium minutissimum, Achnanthidium sp., Sellaphora tridentula, Pinnularia brauniana, Pinnularia divergens var. media, Pinullaria obscura, Pinnularia pseudosudetica, Navicula leptostriata, Nitzschia acidoclinata and Nitzschia semirobusta.

Diatoms taxonomy and ecology

Family STEPHANODISCACEAE

Spicaticribra kingstonii Johansen, Kociolek & Lowe

Figure: 2A

Figure 2
A. Spicaticribra kingstonii; B. Cyclotella meneghiniana; C. Discostella stelligera; D–E. Aulacoseira ambigua; F–G. Aulacoseira tenella; H–I. Fragilaria billingsii; J. Fragilaria capucina; K–L. Fragilaria recapitellata; M–O. Fragilaria tenera; P. Staurosirella pinnata; Q–R. Fragilaria sp., S–T. Staurosira construens; U–V. Eunotia parasiolii; W–X. Eunotia pseudosudetica; Y–Z. Eunotia paratridentula; AA–AB. Eunotia intermedia; AC. Eunotia pyramidata f. capitata; AD. Eunotia rabenhorstii var. monodon; AE. Ulnaria delicatissima; AF. Ulnaria ulna; AG–AH. Eunotia desmogonioides; AI. Eunotia intricans; AJ–AK. Eunotia pseudoimplicata; AL–AN. Eunotia longicamelus; AO–AP. Eunotia minor; AQ. Eunotia subarcuatoides; AR. Eunotia naegelii; AS. Eunotia yanomami.

Valve diameter: 14.8-15.2 µm; areolae: 13 in 10 µm; fultoportulae: 3-5 per valve; rimoportulae: 1-3 per valve.

In Brazil, this species was described by Ludwig et al. (2008)LUDWIG, T.A.V., TREMARIN, P.I., BECKER, V. & TORGAN, L.C. 2008. Thalassiosira rudis sp. nov. (Coscinodiscophyceae): a new freshwater species. Diat. Res. 23(2): 389-400. http://dx.doi.org/10.1080/0269249X.2008.9705765
http://dx.doi.org/10.1080/0269249X.2008....
as Thalassiosira rudis Tremarin, Ludwig, Becker & Torgan and later synonimized with S. kingstonii by Rivera & Cruces (2013)RIVERA, P. & CRUCES, F. 2013. Spicaticribra kingstonii Johansen, Kociolek & Lowe (Thalassiosirales, Bacillariophyta): primera cita del género y de la especie para las aguas continentales de Chile. Gayana Bot. 70(2): 235-240. http://dx.doi.org/10.4067/S0717-66432013000200004
http://dx.doi.org/10.4067/S0717-66432013...
.

Ecology: previously registered in Brazilian tropical and subtropical reservoirs with oligotrophic to eutrophic conditions (Bartozek et al. 2018BARTOZEK, E.C.R., ZORZAL-ALMEIDA, S. & BICUDO, D.C. 2018. Surface sediment and phytoplankton diatoms across a trophic gradient in tropical reservoirs: new records for Brazil and São Paulo State. Hoehnea 45(1): 69-92. http://dx.doi.org/10.1590/2236-8906-51/2017
http://dx.doi.org/10.1590/2236-8906-51/2...
, Silva et al. 2010SILVA, A.M., TREMARIN, P.I., LUDWIG, T.A.V. & VERCELLINO, I.S. 2010. Diatomáceas perifíticas em um sistema eutrófico brasileiro (Reservatório do Iraí, estado do Paraná). Acta Botanica Brasilica . 24(4): 997-1016. http://dx.doi.org/10.1590/S0102-33062010000400015
http://dx.doi.org/10.1590/S0102-33062010...
, Bertolli et al. 2010BERTOLLI, L.M., TREMARIN, P.I. & LUDWIG, T.A.V. 2010. Diatomáceas perifíticas em Polygonum hydropiperoides Michaux, reservatório do Passaúna, Região Metropolitana de Curitiba, Paraná, Brasil. Acta Bot. Bras. 24(4):1065-1081. http://dx.doi.org/10.1590/S0102-33062010000400022
http://dx.doi.org/10.1590/S0102-33062010...
), and neutral pH with moderate conductivity (Ludwig et al. 2008LUDWIG, T.A.V., TREMARIN, P.I., BECKER, V. & TORGAN, L.C. 2008. Thalassiosira rudis sp. nov. (Coscinodiscophyceae): a new freshwater species. Diat. Res. 23(2): 389-400. http://dx.doi.org/10.1080/0269249X.2008.9705765
http://dx.doi.org/10.1080/0269249X.2008....
). In our samples, it occurred in circumneutral pH (6.85), low conductivity (24 µS cm-1) and oligotrophic conditions, only in spring (temperature < 21ºC),

Occurrence in samples: artificial substrates (UPCB 63371).

Cyclotella meneghiniana Kützing

Figure: 2B

Valve diameter: 10-12 µm; striae: 16 in 10 µm; rimoportulae: 1-2 per valve.

Ecology: it is recorded in oligotrophic to eutrophic environments, with a higher abundance in eutrophic waters (Bartozek et al. 2018BARTOZEK, E.C.R., ZORZAL-ALMEIDA, S. & BICUDO, D.C. 2018. Surface sediment and phytoplankton diatoms across a trophic gradient in tropical reservoirs: new records for Brazil and São Paulo State. Hoehnea 45(1): 69-92. http://dx.doi.org/10.1590/2236-8906-51/2017
http://dx.doi.org/10.1590/2236-8906-51/2...
, Silva et al. 2010SILVA, A.M., TREMARIN, P.I., LUDWIG, T.A.V. & VERCELLINO, I.S. 2010. Diatomáceas perifíticas em um sistema eutrófico brasileiro (Reservatório do Iraí, estado do Paraná). Acta Botanica Brasilica . 24(4): 997-1016. http://dx.doi.org/10.1590/S0102-33062010000400015
http://dx.doi.org/10.1590/S0102-33062010...
) and in acidic waters (van Dam et al. 1994). In our samples, it occurred in slightly acid to circumneutral pH (6-6.85), low conductivity (24-24.5 µS cm1) and oligotrophic conditions, in spring and winter (temperature < 21ºC).

Occurrence in samples: artificial (UPCB 63374) and natural (UPCB 63375; UPCB 63378) substrates.

Discostella stelligera (Cleve & Grunow) Houk & Klee

Figure: 2C

Valve diameter: 12-21 µm; striae: 9.6-18.3 in 10 µm.

Ecology: common in oligo-mesotrophic environments (Yang & Dickman 1993YANG, J.R. & DICKMAN, M. 1993. Diatoms as indicators of lake trophic status in central Ontario, Canada. Diat. Res. 8(1): 179-193. http://dx.doi.org/10.1080/0269249X.1993.9705249
http://dx.doi.org/10.1080/0269249X.1993....
, Potapova & Charles 2007POTAPOVA, M. & CHARLES, D.F. 2007. Diatom metrics for monitoring eutrophication in rivers of the United States. Ecol. Indic. 7: 48-70. http://dx.doi.org/10.1016/j.ecolind.2005.10.001
http://dx.doi.org/10.1016/j.ecolind.2005...
), and in alkaline waters with high conductivity (Bartozek et al. 2018BARTOZEK, E.C.R., ZORZAL-ALMEIDA, S. & BICUDO, D.C. 2018. Surface sediment and phytoplankton diatoms across a trophic gradient in tropical reservoirs: new records for Brazil and São Paulo State. Hoehnea 45(1): 69-92. http://dx.doi.org/10.1590/2236-8906-51/2017
http://dx.doi.org/10.1590/2236-8906-51/2...
). It was common in our samples, in slightly acid to circumneutral pH (6-6.85), low conductivity (24-24.5 µS cm-1) and oligotrophic conditions.

Occurrence in samples: artificial (UPCB 63371; UPCB 63372; UPCB 63373; UPCB 63374) and natural (UPCB 63375; UPCB 63376; UPCB 63377; UPCB 63378) substrates.

Family AULACOSEIRACEAE

Aulacoseira ambigua (Grunow) Simonsen

Figures: 2D-2E

Valve diameter: 4-9.4 µm; striae: 8-17 in 10 µm; areolae: 8-17 in 10 µm.

Ecology: this species has a wide ecological tolerance, registered in oligotrophic (Stenger-Kovács et al. 2007STENGER-KOVÁCS, C., BUCZKÓ, K., HAJNAL, E. & PADISÁK, J. 2007. Epiphytic, littoral diatoms as bioindicators of shallow lake trophic status: Trophic diatom index for lakes (TDIL) developed in Hungary. Hydrobiol. 589: 141-154. http://dx.doi.org/10.1007/s10750-007-0729-z
http://dx.doi.org/10.1007/s10750-007-072...
), mesotrophic (Bicudo et al. 2016BICUDO, D.C., TREMARIN, P.I., ALMEIDA, P.D., ZORZAL-ALMEIDA, S., WENGRAT, S., FAUSTINO, S.B., COSTA, L.F., BARTOZEK, E.C.R., ROCHA, A.C.R., BICUDO, C.E.M. & MORALES, E.A. 2016. Ecology and distribution of Aulacoseira species (Bacillariophyta) in tropical reservoirs from Brazil. Diat. Res. 31(3): 199-215. http://dx.doi.org/10.1080/0269249X.2016.1227376
http://dx.doi.org/10.1080/0269249X.2016....
) and meso-eutrophic (Gómez & Licursi 2001GÓMÉZ, N. & LICURSI, M. 2001. The Pampean Diatom Index (IDP) for assessment of rivers and streams in Argentina. Aquatic Ecol. 5: 173-181. http://dx.doi.org/10.1023/A:1011415209445
http://dx.doi.org/10.1023/A:101141520944...
, Ivanov & Kirilova 2004IVANOV, P. & KIRILOVA, E. 2004. Benthic diatoms assemblages from different substrates of the Iskar river, Bulgaria. In Proceeding of the Eighteenth International Diatom Symposium, Miedzyzdroje, Poland (A. Witkowski, ed). p. 107-124., Dela-Cruz et al. 2006DELA-CRUZ, J., PRITCHARD, T., GORDON, G. & AJANI, P. 2006. The use of periphytic diatoms as a means of assessing impacts of point source inorganic nutrient pollution in south-eastern Australia. Freshwat. Biol. 51: 951-972. http://dx.doi.org/10.1111/j.1365-2427.2006.01537.x
http://dx.doi.org/10.1111/j.1365-2427.20...
) environments. In our samples, it occurred in slightly acid to circumneutral pH (6-6.85), low conductivity (24-24.5 µS cm-1) and oligotrophic conditions.

Occurrence in samples: artificial (UPCB 63371; UPCB 63373; UPCB 63374) and natural (UPCB 63375; UPCB 63376; UPCB 63377; UPCB 63378) substrates.

Aulacoseira tenella (Nygaard) Simonsen

Figures: 2F-2G

Valve diameter: 6.3-8 µm; striae: 15 in 10 µm.

Ecology: common in oligotrophic to mesotrophic environments (Bicudo et al. 2016BICUDO, D.C., TREMARIN, P.I., ALMEIDA, P.D., ZORZAL-ALMEIDA, S., WENGRAT, S., FAUSTINO, S.B., COSTA, L.F., BARTOZEK, E.C.R., ROCHA, A.C.R., BICUDO, C.E.M. & MORALES, E.A. 2016. Ecology and distribution of Aulacoseira species (Bacillariophyta) in tropical reservoirs from Brazil. Diat. Res. 31(3): 199-215. http://dx.doi.org/10.1080/0269249X.2016.1227376
http://dx.doi.org/10.1080/0269249X.2016....
, Siver & Kling 1997SIVER, P.A. & KLING, H. 1997. Morphological observations of Aulacoseira using scanning electron microscopy. Can. J. Bot. 75: 1807-1835. http://dx.doi.org/10.1139/b97-894
http://dx.doi.org/10.1139/b97-894...
). In our samples, it occurred in slightly acid to circumneutral pH (6-6.85), low conductivity (24-24.5 µS cm-1) and oligotrophic conditions.

Occurrence in samples: artificial (UPCB 63373; UPCB 63374) and natural (UPCB 63375; UPCB 63376; UPCB 63377; UPCB 63378) substrates.

Family FRAGILARIOPHYCEAE

Fragilaria billingsii Wengrat, Wetzel & Morales

Figures: 2H-2I

Length: 66-73.6 µm; width (central region): 2-2.3 µm; striae: 22 in 10 µm.

Fragilaria billingsii is characterized by long and narrow valves with a bilaterally inflated central area. The striae are distinct and the specimes found in the present study have a higher striae density than those registered by Wengrat et al. (2016)WENGRAT, S., MORALES, E.A., WETZEL, C.E., ALMEIDA, P.D., ECTOR, L. & BICUDO, D.C. 2016. Taxonomy and ecology of Fragilaria billingsii sp. nov. and analysis of type material of Synedra rumpens var. fusa (Fragilariaceae, Bacillariophyta) from Brazil. Phytotaxa. 270(3): 191-202. http://dx.doi.org/10.11646/phytotaxa.270.3.3
http://dx.doi.org/10.11646/phytotaxa.270...
(striae 17-20 in 10 µm).

Ecology: previously registered only for meso-eutrophic environments, with slightly acid pH and low conductivity (Wengrat et al. 2016WENGRAT, S., MORALES, E.A., WETZEL, C.E., ALMEIDA, P.D., ECTOR, L. & BICUDO, D.C. 2016. Taxonomy and ecology of Fragilaria billingsii sp. nov. and analysis of type material of Synedra rumpens var. fusa (Fragilariaceae, Bacillariophyta) from Brazil. Phytotaxa. 270(3): 191-202. http://dx.doi.org/10.11646/phytotaxa.270.3.3
http://dx.doi.org/10.11646/phytotaxa.270...
) In our samples, it occurred in slightly acid to circumneutral pH (6-6.85), low conductivity (24-24.5 µS cm-1) and oligotrophic conditions.

This is the first record for Paraná state.

Occurrence in samples: artificial (UPCB 63371; UPCB 63372; UPCB 63373; UPCB 63374) and natural (UPCB 63375; UPCB 63376; UPCB 63377; UPCB 63378) substrates.

Fragilaria capucina Desmazières

Figure: 2J

Length: 27-34.2 µm; width: 2.8-2.9 µm; striae: 15-16 in 10 µm.

The taxonomy of Fragilaria capucina is very confusing. Based on the type materials, there are three different morphotypes of F. capucina documented in the literature. One of the morphotypes has lanceolate valves; the second one has linear to lanceolate valves that are shorter than in the other two morphotypes, and the third one has a linear valve with a rhombic central area and slightly rostrate valve ends (Tuji & William 2006TUJI, A. & WILLIAMS, D.M. 2007. Type examination of Japanese diatoms described by Friedrich Meister (1913) from lakes Suwa. Bull. Natn. Sci. Mus. 33(2): 69-79., Krammer & Lange-Bertalot 1991aKRAMMER, K. & LANGE-BERTALOT, H. 1991a. Bacillariophyceae: Centrales, Fragilariaceae, Eunotiaceae. In Süsswasserflora von Mitteleuropa (H. Ettl, J. Gerloff, H. Heynig, D. Mollenhauer, eds). Gustav Fischer, Stuttgart. v. 2, pars 3, 576 p.).

Ecology: probably cosmopolitan, found in oligo-mesotrophic (Delgado et al. 2015DELGADO, C., NOVAIS, M.H., BLANCO, S. & ALMEIDA, S.P. 2015. Examination and comparison of Fragilaria candidagilae sp. nov. with type material of Fragilaria recapitellata, F. capucina, F. perminuta, F. intermedia and F. neointermedia (Fragilariales, Bacillariophyceae). Phytotaxa. 231(1): 1-18. http://dx.doi.org/10.11646/phytotaxa.231.1.1
http://dx.doi.org/10.11646/phytotaxa.231...
) to mesotrophic (vam Dam et al. 1994VAN DAM, H., MERTENS, A. & SINKELDAM, J. 1994. A coded checklist and ecological indicator values of freshwater diatoms from the Netherlands. Neth. J. Aquatic Ecol. 28(1): 117-133. http://dx.doi.org/10.1007/BF02334251
http://dx.doi.org/10.1007/BF02334251...
) and eutrophic environments (Hofmann 1994HOFMANN, G. 1994. Aufwuchs-Diatomeen in Seen und ihre Eignung als Indikatoren der Trophie. Biblioth. Diatomol. J. Cramer, Berlin - Stuttgart, 30.). Considered as a planktonic, benthic and terrestrial species (Delgado et al. 2015DELGADO, C., NOVAIS, M.H., BLANCO, S. & ALMEIDA, S.P. 2015. Examination and comparison of Fragilaria candidagilae sp. nov. with type material of Fragilaria recapitellata, F. capucina, F. perminuta, F. intermedia and F. neointermedia (Fragilariales, Bacillariophyceae). Phytotaxa. 231(1): 1-18. http://dx.doi.org/10.11646/phytotaxa.231.1.1
http://dx.doi.org/10.11646/phytotaxa.231...
). In our samples, it occurred attached to artificial substrates and macrophytes, in slightly acid to circumneutral pH (6-6.75), low conductivity (24-24.5 µS cm-1) and oligotrophic conditions.

Occurrence in samples: artificial (UPCB 63372; UPCB 63373; UPCB 63374) and natural (UPCB 63376; UPCB 63377; UPCB 63378) substrates.

Fragilaria recapitellata Lange-Bertalot & Metzeltin

Figures: 2K-2L

Length: 22.2-30.4 µm; width: 2-4 µm; striae: 16-18 in 10 µm.

This species has lanceolate valves with capitate ends and a unilateral central area (Metzeltin et al. 2009METZELTIN, D. , LANGE-BERTALOT, H. & SONINKHISHING, N. 2009. Diatoms in Mongolia. In Iconogr.Diatomol (H. Lange-Bertalot , ed.). Gantner Verlag KG, Ruggell, 20: 3-686.).

Ecology: this species is fairly common in alpha-mesosaprobic and eutrophic conditions (Cantonati et al. 2017CANTONATI, M., KELLY, M.G. & LANGE-BERTALOT, H. 2017. Freshwater benthic diatoms of Central Europe: over 800 common species used in ecological assessment. English edition with update taxonomy and added species. Schmitten-Oberreifenberg: Koeltz Botanical Books. p. 1-942., van Dam et al. 1994). In contrast to previous studies, it was common in our samples, indicating a tolerance to oligotrophic waters, poor in nutrients, with slightly acid to circumneutral pH (6-6.85), and low conductivity (24-24.5 µS cm-1). Although it is cosmopolitan and often present in periphyton samples from lakes, rivers, and streams of temperate regions (Delgado et al. 2015DELGADO, C., NOVAIS, M.H., BLANCO, S. & ALMEIDA, S.P. 2015. Examination and comparison of Fragilaria candidagilae sp. nov. with type material of Fragilaria recapitellata, F. capucina, F. perminuta, F. intermedia and F. neointermedia (Fragilariales, Bacillariophyceae). Phytotaxa. 231(1): 1-18. http://dx.doi.org/10.11646/phytotaxa.231.1.1
http://dx.doi.org/10.11646/phytotaxa.231...
), it is rarely found in tropical regions (Silva et al. 2010SILVA, A.M., TREMARIN, P.I., LUDWIG, T.A.V. & VERCELLINO, I.S. 2010. Diatomáceas perifíticas em um sistema eutrófico brasileiro (Reservatório do Iraí, estado do Paraná). Acta Botanica Brasilica . 24(4): 997-1016. http://dx.doi.org/10.1590/S0102-33062010000400015
http://dx.doi.org/10.1590/S0102-33062010...
, Tremarin et al. 2009TREMARIN, P.I., FREIRE, E.G., BERTOLLI, L.M. & LUDWIG, T.A.V. 2009. Catálogo das diatomáceas (Ochrophyta-Diatomeae) continentais do estado do Paraná. Iheringia - Sér. Bot. 64(2): 79-107.).

Occurrence in samples: artificial (UPCB 63371; UPCB 63372; UPCB 63373; UPCB 63374) and natural (UPCB 63375; UPCB 63378) substrates.

Fragilaria tenera (W. Smith) Lange-Bertalot

Figures: 2M-2O

Length: 38.8-51.8 µm; width: 2.3-2.8 µm; striae: 15 in 10 µm.

The specimens analyzed in the present study are shorter, with a lower striae density, and the absence of a central area. Hofmann et al. (2013)HOFMANN, G., WERUM, M. & LANGE-BERTALOT, H. 2013. Diatomeen im Süßwasser - Benthos von Mitteleuropa. Bestimmungsflora Kieselalgen für die ökologische Praxis. Über 700 der häufigsten Arten und ihre Ökologie.Koeltz Scientific Books, Königstein. referred specimens of 30-100 µm long, 2-3 µm wide and with a striae density of 17-20 in 10 µm, and the often absence of a central area.

Ecology: this species was registered for oligo-mesotrophic environments (van Dam et al. 1994VAN DAM, H., MERTENS, A. & SINKELDAM, J. 1994. A coded checklist and ecological indicator values of freshwater diatoms from the Netherlands. Neth. J. Aquatic Ecol. 28(1): 117-133. http://dx.doi.org/10.1007/BF02334251
http://dx.doi.org/10.1007/BF02334251...
). In our samples it occurred attached to the substrates in slightly acid to circumneutral pH (6-6.85), low conductivity (24-24.5 µS cm-1) and oligotrophic conditions.

Occurrence in samples: artificial (UPCB 63371; UPCB 63372; UPCB 63373; UPCB 63374) and natural (UPCB 63376; UPCB 63377) substrates.

Fragilaria sp.

Figures: 2Q-2R

Length: 24.5-31.7 µm; width: 2.3-3.1 µm; striae: 16-17 in 10 µm.

Fragilaria sp. resembles Fragilaria austriaca (Grunow) Lange-Bertalot in the outline but has wider valves (3-4 µm) and a lower striae density (12-15 µm). Fragilaria pararumpens Lange-Bertalot, Hofmann & Werum has similar dimensions to Fragilaria sp., but a more lanceolate valve with subcapitate ends (Cantonati et al. 2017CANTONATI, M., KELLY, M.G. & LANGE-BERTALOT, H. 2017. Freshwater benthic diatoms of Central Europe: over 800 common species used in ecological assessment. English edition with update taxonomy and added species. Schmitten-Oberreifenberg: Koeltz Botanical Books. p. 1-942.).

Ecology: In our samples, it occurred only in temperatures < 21ºC, slightly acid to circumneutral pH (6-6.75), low conductivity (22.5-24.5 µS cm-1) and oligotrophic conditions.

Occurrence in samples: artificial (UPCB 63371; UPCB 63373; UPCB 63374) and natural (UPCB 63378) substrates.

Family STAUROSIRACEAE

Staurosira construens Ehrenberg

Figures: 2S-2T

Length: 15.7 µm; width: 8.6 µm; striae: 18 in 10 µm.

Ecology: this species is registered for meso-eutrophic environments (van Dam et al. 1994) and is considered as tolerant to different water conditions (Hofmann 1994HOFMANN, G. 1994. Aufwuchs-Diatomeen in Seen und ihre Eignung als Indikatoren der Trophie. Biblioth. Diatomol. J. Cramer, Berlin - Stuttgart, 30.). In our samples, it occurred in slighltly acid pH (6), low conductivity (24.5 µS cm-1) and oligotrophic conditions, only in winter (temperature 16ºC).

Occurrence in samples: natural substrates (UPCB 63378).

Staurosirella pinnata (Ehrenberg) Williams & Round.

Figure: 2P

Length: 8-14.4 µm; width: 3.3-3.8 µm; striae: 8-11 in 10 µm.

Ecology: this species is considered as tolerant (Hofmann 1994HOFMANN, G. 1994. Aufwuchs-Diatomeen in Seen und ihre Eignung als Indikatoren der Trophie. Biblioth. Diatomol. J. Cramer, Berlin - Stuttgart, 30.) to indifferent (van Dam et al. 1994) to the trophic state. In our samples, it occurred in slighltly acid pH (6), low conductivity (24.5 µS cm-1) and oligotrophic condition, only in winter (temperature 16ºC).

Occurrence in samples: artificial substrates (UPCB 63374).

Family ULNARIACEAE

Ulnaria delicatissima (Smith) Aboal & Silva

Figure: 2AE

Length: 62.4-109.5 µm; width: 2.4-4.7 µm; striae: 13-16 in 10 µm.

Ecology: common in oligo-mesotrophic environments (van Dam et al. 1994, Hofmann 1994HOFMANN, G. 1994. Aufwuchs-Diatomeen in Seen und ihre Eignung als Indikatoren der Trophie. Biblioth. Diatomol. J. Cramer, Berlin - Stuttgart, 30.). In our samples, it occurred in slighltly acid to circumneutral pH (6-6.85), low conductivity (24-24.5 µS cm-1) and oligotrophic conditions.

Occurrence in samples: artificial (UPCB 63371; UPCB 63372; UPCB 63374) and natural (UPCB 63375; UPCB 63378) substrates.

Ulnaria ulna (Nitzsch) Compère.

Figure: 2AF

Length: 90-189 µm; width: 4-4.8 µm; striae: 9-14 in 10 µm.

Ecology: considered as indifferent to tolerant to the trophic state of the environment (van Dam et al. 1994, Hofmann 1994HOFMANN, G. 1994. Aufwuchs-Diatomeen in Seen und ihre Eignung als Indikatoren der Trophie. Biblioth. Diatomol. J. Cramer, Berlin - Stuttgart, 30.). In our samples, it occurred in circumneutral pH (6.75), low conductivity (24.5 µS cm-1) and oligotrophic conditions, only in summer (temperature of 27ºC and accumulated rainfall 326.9 mm).

Occurrence in samples: natural substrates (UPCB 63376).

Family EUNOTIACEAE

Eunotia desmogonioides Metzeltin & Lange-Bertalot

Figures: 2AG-2AH

Length: 99-159.3 µm; width: 3.5-5 µm; striae: 17-20 in 10 µm.

This species has a valve outline similar to Eunotia flexuosa (Brébisson) Kützing, although with narrower valves and a higher striae density. Eunotia rabenhorstiana var. elongata (Patrick) Metzeltin & Lange-Bertalot is similar to E. flexuosa but has wider valves with more inflated ends (Costa et al. 2017COSTA, L.F., WETZEL, C.E., LANGE-BERTALOT, H., ECTOR, L. & BICUDO, D.C. 2017. Taxonomy and ecology of Eunotia species (Bacillariophyta) in southeastern Brazilian reservoirs. Biblioth. Diatomol. 64: 1-302.).

Ecology: previously registered for Brazilian oligo- to mesotrophic reservoirs, with low conductivity and slightly acidic to neutral pH (Costa et al. 2017COSTA, L.F., WETZEL, C.E., LANGE-BERTALOT, H., ECTOR, L. & BICUDO, D.C. 2017. Taxonomy and ecology of Eunotia species (Bacillariophyta) in southeastern Brazilian reservoirs. Biblioth. Diatomol. 64: 1-302.). In our samples, it occurred in slightly acid to circumneutral pH (6-6.85), low conductivity (22.5-24.5 µS cm-1) and oligotrophic conditions.

Occurrence in samples: artificial (UPCB 63371, UPCB 63372, UPCB 63373) and natural (UPCB 63375, UPCB 63376, UPCB 63377, UPCB 63378) substrates.

Eunotia intermedia (Krasske ex Hustedt) Nörpel & Lange-Bertalot

Figures: 2AA-2AB

Length: 13.3-16.8 µm; width: 3.1-3.3 µm; striae: 14-15 in 10 µm.

Ecology: previously registered for slightly acidic waters with low conductivity (Lange-Bertalot et al. 2011LANGE-BERTALOT, H.; BAK, M. & WITKOWSKI, A. 2011. Eunotia and some related genera. In: Diatoms of Europe (Lange-Bertalot, H., ed.). Königstein, Koeltz Scientific Books, 6.). In our samples, it occurred in circumneutral pH (6.85), low conductivity (24 µS cm-1) and oligotrophic conditions, only in spring (temperature < 21ºC).

Occurrence in samples: artificial substrate (UPCB 63371).

Eunotia intricans Lange-Bertalot & Metzeltin

Figure: 2AI

Length: 35-51.7 µm; width: 4.5-5.1 µm; striae: 11-13 in 10 µm.

Eunotia intricans is similar to Eunotia parasiolii Metzeltin & Lange-Bertalot in the valve outline, although it has a lower striae density (6.5-11/10 µm, according to Metzeltin & Lange-Bertalot 1998METZELTIN, D. & LANGE-BERTALOT, H. 1998. Tropical diatoms of South America I. About 700 predominantly rarely known or new taxa representative of the neotropical flora. In Iconogr. Diatomol. (H. Lange-Bertalot , ed.) 5: 1-695.). In Piraquara reservoir, the specimens were longer than the type specimen (17-48 µm, according to Lange-Bertalot & Metzeltin 2009METZELTIN, D. , LANGE-BERTALOT, H. & SONINKHISHING, N. 2009. Diatoms in Mongolia. In Iconogr.Diatomol (H. Lange-Bertalot , ed.). Gantner Verlag KG, Ruggell, 20: 3-686.), but have a similar length to other specimens registered in Brazilian reservoirs (Costa et al. 2017COSTA, L.F., WETZEL, C.E., LANGE-BERTALOT, H., ECTOR, L. & BICUDO, D.C. 2017. Taxonomy and ecology of Eunotia species (Bacillariophyta) in southeastern Brazilian reservoirs. Biblioth. Diatomol. 64: 1-302.).

Ecology: previously registered for oligo-mesotrophic environments, with a preference for acid waters with low conductivity (Costa et al. 2017COSTA, L.F., WETZEL, C.E., LANGE-BERTALOT, H., ECTOR, L. & BICUDO, D.C. 2017. Taxonomy and ecology of Eunotia species (Bacillariophyta) in southeastern Brazilian reservoirs. Biblioth. Diatomol. 64: 1-302.). In our samples, it occurred in circumneutral pH (6.7-6.85), low conductivity (22.5-24 µS cm-1) and oligotrophic conditions, in spring and autumn (temperature < 21ºC).

Occurrence in samples: natural substrates (UPCB 63375, 63377).

Eunotia longicamelus Costa, Bicudo & Wetzel

Figure: 2AL-2AN

Length: 16.2-52.6 µm; width: 5.4-5.26 µm; striae: 11 in 10 µm; valvar undulations: 2-4.

Similar to Eunotia camelus Ehrenberg, but differs in the type and number of undulations on the dorsal margin (two undulations subdivided into two more) and the presence of wider valves (length: 22-30 µm; width: 6-8.8 µm; striae density 8-12 in 10 µm and two undulations) (Costa et al. 2017COSTA, L.F., WETZEL, C.E., LANGE-BERTALOT, H., ECTOR, L. & BICUDO, D.C. 2017. Taxonomy and ecology of Eunotia species (Bacillariophyta) in southeastern Brazilian reservoirs. Biblioth. Diatomol. 64: 1-302., Reichardt 1995REICHARDT, E. 1995. Die Diatomeen (Bacillariophyceae) in Ehrenberg's material von Cayenne, Guyana Gallica (1843). In Iconogr. Diatomol. (H. Lange-Bertalot , ed.) 1: 1-107.).

Ecology: previously registered for mesotrophic environments, with a preference for slightly acidic waters (pH 6.6) with medium values of conductivity (71 µS cm-1) (Costa et al. 2017COSTA, L.F., WETZEL, C.E., LANGE-BERTALOT, H., ECTOR, L. & BICUDO, D.C. 2017. Taxonomy and ecology of Eunotia species (Bacillariophyta) in southeastern Brazilian reservoirs. Biblioth. Diatomol. 64: 1-302.). In our samples, it occurred only in winter (temperature 16ºC) and expanded the occurrence to oligotrophic environments with slightly acid pH (6), and low conductivity (24.5 µS cm-1).

This is the first record for Paraná state.

Occurrence in samples: natural substrates (UPCB 63378).

Eunotia minor (Kützing) Grunow.

Figures: 2AO-2AP

Length: 17-24.7 µm; width: 3.8 µm; striae: 17-18 in 10 µm.

Ecology: considered as tolerant to different trophic states, ranging from oligo- to eutrophic (van Dam et al. 1994, Hofmann 1994HOFMANN, G. 1994. Aufwuchs-Diatomeen in Seen und ihre Eignung als Indikatoren der Trophie. Biblioth. Diatomol. J. Cramer, Berlin - Stuttgart, 30.). In our samples, it occurred in slightly acid pH (6), low conductivity (24.5 µS cm-1) and oligotrophic conditions, only in winter (temperature 16ºC).

Occurrence in samples: natural substrates (UPCB 63378).

Eunotia naegelii Migula.

Figure: 2AR

Length: 40-48.4 µm; width: 1.8-3 µm; striae: 21-24 in 10 µm.

Ecology: considered as acidophile; registered for ultra-oligotrophic to oligotrophic environments (Costa et al. 2017COSTA, L.F., WETZEL, C.E., LANGE-BERTALOT, H., ECTOR, L. & BICUDO, D.C. 2017. Taxonomy and ecology of Eunotia species (Bacillariophyta) in southeastern Brazilian reservoirs. Biblioth. Diatomol. 64: 1-302., van Dam et al. 1994). In our samples, it occurred in slightly acid pH (6), low conductivity (24.5 µS cm-1) and oligotrophic conditions, only in winter (temperature 16ºC).

Occurrence in samples: natural substrates (UPCB 63378).

Eunotia parasiolii Metzeltin & Lange-Bertalot.

Figures: 2U-2V

Length: 18.5-32.6µm; width: 3-4.7 µm; striae: 9-12 in 10 µm.

Ecology: previously registered for acidic waters (pH 4.4-5.3) with a low conductivity (9.4-12.6 µS cm-1) (Ferrari et al. 2007FERRARI, F., PROCOPIAK, L.K., ALENCAR, Y.B. & LUDWIG, T.A.V. 2007. Eunotiaceae (Bacillariophyceae) em igarapés da Amazônia Central, Manaus e Presidente Figueiredo, Brasil. Acta Amaz. 37(1): 1-16. http://dx.doi.org/10.1590/S0044-59672007000100001
http://dx.doi.org/10.1590/S0044-59672007...
) to slightly acidic (pH 6.6-6.8) and oligotrophic environments (Costa et al. 2017COSTA, L.F., WETZEL, C.E., LANGE-BERTALOT, H., ECTOR, L. & BICUDO, D.C. 2017. Taxonomy and ecology of Eunotia species (Bacillariophyta) in southeastern Brazilian reservoirs. Biblioth. Diatomol. 64: 1-302.). In our samples, it occurred in circumneutral pH (6.85), low conductivity (24 µS cm-1) and oligotrophic conditions, only in spring (temperature < 21ºC).

Occurrence in samples: natural substrates (UPCB 63375).

Eunotia paratridentula Lange-Bertalot & Kulikovskyi.

Figures: 2Y-2Z

Length: 13-17.6 µm; width: 2.8-4 µm; striae: 14-16 in 10 µm; undulations: 3-4.

Previously reported for Paraná State as Eunotia muscicola Krasske var. tridentula Nörpel & Lange-Bertalot (Tremarin et al. 2009TREMARIN, P.I., FREIRE, E.G., BERTOLLI, L.M. & LUDWIG, T.A.V. 2009. Catálogo das diatomáceas (Ochrophyta-Diatomeae) continentais do estado do Paraná. Iheringia - Sér. Bot. 64(2): 79-107.). It differs from E. muscicola Krasske by the lower striae density; and from E. paramuscicola Krstić, Levkov & Pavlov by the broadly protracted apices (Krstić et al. 2013KRSTIĆ, S.S., PAVLOV, A., LEVKOV, Z. & JÜTTNER, I. 2013. New Eunotia taxa in core samples from Lake Panch Pokhari in the Nepalese Himalaya. Diat. Res. 28(2): 203-217. http://dx.doi.org/10.1080/0269249X.2013.782343
http://dx.doi.org/10.1080/0269249X.2013....
).

Ecology: considered as acidophile (van Dam et al. 1994VAN DAM, H., MERTENS, A. & SINKELDAM, J. 1994. A coded checklist and ecological indicator values of freshwater diatoms from the Netherlands. Neth. J. Aquatic Ecol. 28(1): 117-133. http://dx.doi.org/10.1007/BF02334251
http://dx.doi.org/10.1007/BF02334251...
); registered for mesotrophic environments (Marra et al. 2016MARRA, R.C., TREMARIN, P.I., ALGARTE, V.M. & LUDWIG, T.A. 2016. Epiphytic diatoms (Diatomeae) from Piraquara II urban reservoir, Paraná state. Biotaneotropica 16(4): e20160200. http://dx.doi.org/10.1590/1676-0611-BN-2016-0200
http://dx.doi.org/10.1590/1676-0611-BN-2...
). Our study expanded its occurrence to environments with pH ranging from slightly acid to circumneutral (6-6.85), low conductivity (22.5-24.5 µS cm-1) and oligotrophic conditions.

Occurrence in samples: artificial (UPCB 63371; UPCB 63373) and natural (UPCB 63375; UPCB 63376; UPCB 63378) substrates.

Eunotia pseudoimplicata Lange-Bertalot, Costa & Wetzel

Figures: 2AJ-2AK

Length: 28.7-43 µm; width: 4.2-5.3 µm; striae: 14-16 in 10 µm.

Ecology: oligo-mesotrophic reservoirs, with slightly acid to neutral waters (Costa et al. 2017COSTA, L.F., WETZEL, C.E., LANGE-BERTALOT, H., ECTOR, L. & BICUDO, D.C. 2017. Taxonomy and ecology of Eunotia species (Bacillariophyta) in southeastern Brazilian reservoirs. Biblioth. Diatomol. 64: 1-302.). In our samples, it occurred in circumneutral pH (6.85), low conductivity (24 µS cm-1) and oligotrophic conditions, only in spring (temperature < 21ºC).

This is the first record for Paraná state.

Occurrence in samples: artificial (UPCB 63371) and natural (UPCB 63375) substrates.

Eunotia pseudosudetica Metzeltin, Lange-Bertalot & García-Rodríguez

Figures: 2W-2X

Length: 30.4-33.26 µm; width: 4.9-5.4 µm; striae: 12 in 10 µm.

Ecology: this species occurred in slightly acidic to circumneutral pH (6-6.85), low conductivity (22.5-24 µS cm-1) and in oligotrophic conditions, in agreement with previously studies (Costa et al. 2017COSTA, L.F., WETZEL, C.E., LANGE-BERTALOT, H., ECTOR, L. & BICUDO, D.C. 2017. Taxonomy and ecology of Eunotia species (Bacillariophyta) in southeastern Brazilian reservoirs. Biblioth. Diatomol. 64: 1-302.), but can also be registered for nutrient-rich environments (Bertolli et al. 2010BERTOLLI, L.M., TREMARIN, P.I. & LUDWIG, T.A.V. 2010. Diatomáceas perifíticas em Polygonum hydropiperoides Michaux, reservatório do Passaúna, Região Metropolitana de Curitiba, Paraná, Brasil. Acta Bot. Bras. 24(4):1065-1081. http://dx.doi.org/10.1590/S0102-33062010000400022
http://dx.doi.org/10.1590/S0102-33062010...
, Faria et al. 2010FARIA, D.M., TREMARIN, P.I. & LUDWIG, T.A.V. 2010. Diatomáceas perifíticas da represa Itaqui, São José dos Pinhais, Paraná: Fragilariales, Eunotiales, Achnanthales, e Gomphonema Ehrenberg. Biota Neotropica 10(3): http://www.biotaneotropica.org.br/v10n3/pt/abstract?inventory+bn04110032010
http://www.biotaneotropica.org.br/v10n3/...
, Marra et al. 2016MARRA, R.C., TREMARIN, P.I., ALGARTE, V.M. & LUDWIG, T.A. 2016. Epiphytic diatoms (Diatomeae) from Piraquara II urban reservoir, Paraná state. Biotaneotropica 16(4): e20160200. http://dx.doi.org/10.1590/1676-0611-BN-2016-0200
http://dx.doi.org/10.1590/1676-0611-BN-2...
). Usually found in the periphyton, but can be also registered from phytoplankton (Bartozek et al. 2013BARTOZEK, E.C.R., BUENO, N.C., LUDWIG, T.A.V., TREMARIN, T.A.V., NARDELLI, M.S. & ROCHA, A.C.R. 2013. Diatoms (Bacillariophyceae) of Iguaçu National Park, Foz do Iguaçu, Brazil. Acta Botanica Brasilica 27(1): 108-123. http://dx.doi.org/10.1590/S0102-33062013000100012
http://dx.doi.org/10.1590/S0102-33062013...
) and surface sediments (Costa et al. 2017COSTA, L.F., WETZEL, C.E., LANGE-BERTALOT, H., ECTOR, L. & BICUDO, D.C. 2017. Taxonomy and ecology of Eunotia species (Bacillariophyta) in southeastern Brazilian reservoirs. Biblioth. Diatomol. 64: 1-302.).

Occurrence in samples: artificial (UPCB 63371; UPCB 63372; UPCB 63373) and natural (UPCB 63375; UPCB 63376; UPCB 63377; UPCB 63378) substrates.

Eunotia pyramidata f. capitata Krasske

Figure: 2AC

Length: 25.5 µm; width: 4.6 µm; striae: 15 in 10 µm; undulations: 3.

It differs from Eunotia rabenhorstii var. triodon Cleve & Grunow by the presence of a more pronounced mark in the central undulation (Costa et al. 2017COSTA, L.F., WETZEL, C.E., LANGE-BERTALOT, H., ECTOR, L. & BICUDO, D.C. 2017. Taxonomy and ecology of Eunotia species (Bacillariophyta) in southeastern Brazilian reservoirs. Biblioth. Diatomol. 64: 1-302.).

Ecology: previously registered for moody pools with sphagnum moss (Krasske 1948KRASSKE, G. 1948. Diatomeen tropischer Moosrasen. Svensk Botanisk Tidskrift 42(4): 404-443.), and from samples of surface sediments collected in environments with acid pH and poor in nutrients (Costa et al. 2017COSTA, L.F., WETZEL, C.E., LANGE-BERTALOT, H., ECTOR, L. & BICUDO, D.C. 2017. Taxonomy and ecology of Eunotia species (Bacillariophyta) in southeastern Brazilian reservoirs. Biblioth. Diatomol. 64: 1-302.). In our samples, it occurred in circumneutral pH (6.7), low conductivity (22.5 µS cm-1) and oligotrophic conditions, only in autumn (temperature 18.6ºC).

Occurrence in samples: natural substrates (UPCB 63377).

Eunotia rabenhorstii var. monodon Cleve & Grunow

Figure: 2AD

Length: 20 µm; width: 6.2 µm; striae: 17 in 10 µm.

Ecology: previously registered for a mesotrophic reservoir in Paraná state (Bertolli et al. 2010BERTOLLI, L.M., TREMARIN, P.I. & LUDWIG, T.A.V. 2010. Diatomáceas perifíticas em Polygonum hydropiperoides Michaux, reservatório do Passaúna, Região Metropolitana de Curitiba, Paraná, Brasil. Acta Bot. Bras. 24(4):1065-1081. http://dx.doi.org/10.1590/S0102-33062010000400022
http://dx.doi.org/10.1590/S0102-33062010...
, Marra et al. 2016MARRA, R.C., TREMARIN, P.I., ALGARTE, V.M. & LUDWIG, T.A. 2016. Epiphytic diatoms (Diatomeae) from Piraquara II urban reservoir, Paraná state. Biotaneotropica 16(4): e20160200. http://dx.doi.org/10.1590/1676-0611-BN-2016-0200
http://dx.doi.org/10.1590/1676-0611-BN-2...
) and for ultraoligotrophic to eutrophic reservoirs with slightly acidic to alkaline waters (pH 6.2-7.3) in São Paulo state (Costa et al. 2017COSTA, L.F., WETZEL, C.E., LANGE-BERTALOT, H., ECTOR, L. & BICUDO, D.C. 2017. Taxonomy and ecology of Eunotia species (Bacillariophyta) in southeastern Brazilian reservoirs. Biblioth. Diatomol. 64: 1-302.). In our samples, it occurred in circumneutral pH (6.7-6.75), low conductivity (22.5-24.5 µS cm-1) and oligotrophic conditions, in summer and autumn (temperature from 18.6-27ºC).

Occurrence in samples: natural substrates (UPCB 63376; UPCB 63377).

Eunotia subarcuatoides Alles, Nörpel & Lange-Bertalot

Figure: 2AQ

Length: 13.5-17.3 µm; width: 2.4-2.9 µm; striae: 23-24 in 10 µm.

Similar to the small forms of Eunotia bilunaris (Ehrenberg) Schaarschmidt, but with a lower density of striae (13-17 in 10 µm) that are less conspicuous (Costa et al. 2017COSTA, L.F., WETZEL, C.E., LANGE-BERTALOT, H., ECTOR, L. & BICUDO, D.C. 2017. Taxonomy and ecology of Eunotia species (Bacillariophyta) in southeastern Brazilian reservoirs. Biblioth. Diatomol. 64: 1-302.). The specimens found herein presented a less width than the type material (3-4.5 µm, according to Alles et al. 1991ALLES, E., NÖRPEL-SCHEMPP, M. & LANGE-BERTALOT, H. 1991. Zur Systematik und Ökologie charakteristischer Eunotia-Arten (Bacillariophyceae) in elektrolytarmen Bachoberläufen. Nova Hedwigia 53 (1-2): 171-213.), but presented a similar width to the specimens (2.5-3.3 µm) registered by Costa et al. (2017)COSTA, L.F., WETZEL, C.E., LANGE-BERTALOT, H., ECTOR, L. & BICUDO, D.C. 2017. Taxonomy and ecology of Eunotia species (Bacillariophyta) in southeastern Brazilian reservoirs. Biblioth. Diatomol. 64: 1-302. in Brazilian reservoirs.

Ecology: considered as acidobiontic (van Dam et al. 1994). In Brazil, it was previously registered for ultraoligo to eutrophic conditions (Costa et al. 2017COSTA, L.F., WETZEL, C.E., LANGE-BERTALOT, H., ECTOR, L. & BICUDO, D.C. 2017. Taxonomy and ecology of Eunotia species (Bacillariophyta) in southeastern Brazilian reservoirs. Biblioth. Diatomol. 64: 1-302., Silva et al. 2010SILVA, A.M., TREMARIN, P.I., LUDWIG, T.A.V. & VERCELLINO, I.S. 2010. Diatomáceas perifíticas em um sistema eutrófico brasileiro (Reservatório do Iraí, estado do Paraná). Acta Botanica Brasilica . 24(4): 997-1016. http://dx.doi.org/10.1590/S0102-33062010000400015
http://dx.doi.org/10.1590/S0102-33062010...
), with acid to alkaline pH (Costa et al. 2017COSTA, L.F., WETZEL, C.E., LANGE-BERTALOT, H., ECTOR, L. & BICUDO, D.C. 2017. Taxonomy and ecology of Eunotia species (Bacillariophyta) in southeastern Brazilian reservoirs. Biblioth. Diatomol. 64: 1-302.). In our samples, it occurred in slightly acid to circumneutral pH (6-6.85), low conductivity (22.5-24.5 µS cm-1) and oligotrophic conditions.

Occurrence in samples: natural substrates (UPCB 63375; UPCB 63376; UPCB 63377; UPCB 63378).

Eunotia yanomami Metzeltin & Lange-Bertalot

Figure: 2AS

Length: 120 µm; width: 13.5 µm; striae: 15 in 10 µm; undulations: 4.

Similar to Eunotia zygodon Ehrenberg in the valve outline, but E. zygodon has a smaller size (less than 55 µm in length, according to Metzeltin & Lange-Bertalot 1998METZELTIN, D. & LANGE-BERTALOT, H. 1998. Tropical diatoms of South America I. About 700 predominantly rarely known or new taxa representative of the neotropical flora. In Iconogr. Diatomol. (H. Lange-Bertalot , ed.) 5: 1-695.).

Ecology: previously registered for oligotrophic to mesotrophic environments (Marra et al. 2016MARRA, R.C., TREMARIN, P.I., ALGARTE, V.M. & LUDWIG, T.A. 2016. Epiphytic diatoms (Diatomeae) from Piraquara II urban reservoir, Paraná state. Biotaneotropica 16(4): e20160200. http://dx.doi.org/10.1590/1676-0611-BN-2016-0200
http://dx.doi.org/10.1590/1676-0611-BN-2...
, Costa et al. 2017COSTA, L.F., WETZEL, C.E., LANGE-BERTALOT, H., ECTOR, L. & BICUDO, D.C. 2017. Taxonomy and ecology of Eunotia species (Bacillariophyta) in southeastern Brazilian reservoirs. Biblioth. Diatomol. 64: 1-302.), with slightly acid waters (pH 5.4-6.4) and low to medium conductivity (12-70 µS cm-1) (Bicca & Torgan 2009BICCA, A.B. & TORGAN, L.C. 2009. Novos registros de Eunotia Ehrenberg (Eunotiaceae-Bacillariophyta) para o Estado do Rio Grande do Sul e Brasil. Acta Bot. Bras. 23(2): 427-435. http://dx.doi.org/10.1590/S0102-33062009000200014
http://dx.doi.org/10.1590/S0102-33062009...
). In our samples, it occurred in circumneutral pH (6.7), low conductivity (22.5 µS cm-1) and oligotrophic conditions, only in autumn (temperature 18.6ºC).

Occurrence in samples: natural substrates (UPCB 63377).

Family GOMPHONEMATACEAE

Placoneis elginensis (Gregory) Cox

Figure: 3A

Figure 3
A. Placoneis elginensis; B–C. Encyonema neogracile; D. Encyonema silesiacum; E. Encyonopsis schubartii; F. Encyonopsis subminuta; G–I. Gomphonema spiculoides; J–K. Gomphonema gracile; L–M. Gomphonema lagenula; N–O. Gomphonema pantropicum; P. Cymbopleura naviculiformis; Q–S. Encyonopsis cf. reichardtii; T–W. Achnanthidium minutissimum; X–AD. Achnanthidium neomicrocephalum; AE–AH. Achnanthidium sp.; AI–AJ. Planothidium incuriatum; AK. Humidophila biscutella; AL. Luticola permuticoides; AM. Luticola simplex; AN–AP. Frustulia australocrassinervia; 3AQ–3AS. Frustulia undosa; AT–AV. Brachysira neoexilis; AW–AX. Neidium affine.

Length: 34.7 µm; width: 10 µm; striae: 13 in 10 µm.

Ecology: previously registered for highly alkaline waters, and for mesotrophic and eutrophic environments (van Dam et al. 1994, Hofmann 1994HOFMANN, G. 1994. Aufwuchs-Diatomeen in Seen und ihre Eignung als Indikatoren der Trophie. Biblioth. Diatomol. J. Cramer, Berlin - Stuttgart, 30., Poulíčková et al. 2008POULÍČKOVÁ, A., ŠPAČKOVÁ, J., KELLY, M.G., DUCHOSLAV, M. & MANN, D.G. 2008. Ecological variation within Sellaphora species complexes (Bacillariophyceae): specialists or generalists? Hydrobiologia 614: 373-386. http://dx.doi.org/10.1007/s10750-008-9521-y
http://dx.doi.org/10.1007/s10750-008-952...
). In our samples, it occurred in circumneutral pH (6.7), low conductivity (22.5 µS cm-1) and oligotrophic conditions, only in autumn (temperature 18.6ºC).

Occurrence in samples: artificial substrates (UPCB 63373).

Encyonema neogracile Krammer.

Figures: 3B-3C

Length: 35.5-56.6 µm; width: 6.5-7.5 µm; dorsal striae: 14 in 10 µm; ventral striae: 15-16 in 10 µm.

Ecology: this species was frequent in our samples and occurred in slightly acid to circumneutral pH (6-6.85), low conductivity (22.5-24.5 µS cm-1) and oligotrophic conditions, but was also previously registered for oligo-mesotrophic and mesotrophic environments (van Dam et al. 1994VAN DAM, H., MERTENS, A. & SINKELDAM, J. 1994. A coded checklist and ecological indicator values of freshwater diatoms from the Netherlands. Neth. J. Aquatic Ecol. 28(1): 117-133. http://dx.doi.org/10.1007/BF02334251
http://dx.doi.org/10.1007/BF02334251...
, Marra et al. 2016MARRA, R.C., TREMARIN, P.I., ALGARTE, V.M. & LUDWIG, T.A. 2016. Epiphytic diatoms (Diatomeae) from Piraquara II urban reservoir, Paraná state. Biotaneotropica 16(4): e20160200. http://dx.doi.org/10.1590/1676-0611-BN-2016-0200
http://dx.doi.org/10.1590/1676-0611-BN-2...
).

Occurrence in samples: artificial (UPCB 63371; UPCB 63372; UPCB 63373; UPCB 63374) and natural (UPCB 63375; UPCB 63376; UPCB 63377; UPCB 63378) substrates.

Encyonema silesiacum (Bleisch) Mann.

Figure: 3D

Length: 17.4-21.5 µm; width: 5-7.5 µm; dorsal striae: 11-17 in 10 µm; ventral striae: 12-16 in 10 µm.

Ecology: widely distributed, considered as a circumneutral species (van Dam et al. 1994), occurring in waters ranging from oligo to eutrophic (van Dam et al. 1994, Hofmann 1994HOFMANN, G. 1994. Aufwuchs-Diatomeen in Seen und ihre Eignung als Indikatoren der Trophie. Biblioth. Diatomol. J. Cramer, Berlin - Stuttgart, 30., Bertolli et al. 2010BERTOLLI, L.M., TREMARIN, P.I. & LUDWIG, T.A.V. 2010. Diatomáceas perifíticas em Polygonum hydropiperoides Michaux, reservatório do Passaúna, Região Metropolitana de Curitiba, Paraná, Brasil. Acta Bot. Bras. 24(4):1065-1081. http://dx.doi.org/10.1590/S0102-33062010000400022
http://dx.doi.org/10.1590/S0102-33062010...
, Silva et al. 2010SILVA, A.M., TREMARIN, P.I., LUDWIG, T.A.V. & VERCELLINO, I.S. 2010. Diatomáceas perifíticas em um sistema eutrófico brasileiro (Reservatório do Iraí, estado do Paraná). Acta Botanica Brasilica . 24(4): 997-1016. http://dx.doi.org/10.1590/S0102-33062010000400015
http://dx.doi.org/10.1590/S0102-33062010...
, Marra et al. 2016MARRA, R.C., TREMARIN, P.I., ALGARTE, V.M. & LUDWIG, T.A. 2016. Epiphytic diatoms (Diatomeae) from Piraquara II urban reservoir, Paraná state. Biotaneotropica 16(4): e20160200. http://dx.doi.org/10.1590/1676-0611-BN-2016-0200
http://dx.doi.org/10.1590/1676-0611-BN-2...
). This study expands its occurrence to slightly acid pH (6-6.85), low conductivity (24-24.5 µS cm-1) and oligotrophic conditions.

Occurrence in samples: artificial (UPCB 6371) and natural (UPCB 63375; UPCB 63376; UPCB 63378) substrates.

Encyonopsis cf. reichardtii Krammer

Figures: 3Q-3S

Length: 36.5-40 µm; width: 5.8-6 µm; maximum ratio L/W= 6.8; dorsal striae: 18-20 in 10 µm; ventral striae: 17-21 in 10 µm.

The specimens from Piraquara I reservoir presented the valve outline, striation pattern, and isolated punctum near the central striae similar to Encyonopsis reichardtii Krammer. As the type specimens have a slightly more rhombo-lanceolate contour, wider valves (7-7.7 µm) and a maximum ratio L/W of 6.1 (Krammer 1997bKRAMMER, K. 1997b. Die cymbelloidean Diatomeen: eine Monographie der weltweit bekannten taxa. II Encyonema part., Encyonopsis and Cymbellopsis. Biblioth. Diatomol. 37: 1-469. Verlag KG, Ruggell, v. 3, 584 p.: 131) we preferred to identify the taxon as conferatum.

Ecology: this species occurred in slightly acid to circumneutral pH (6-6.75), low conductivity (22.5-24.5 µS cm-1) and oligotrophic conditions.

Occurrence in samples: artificial (UPCB 63372; UPCB 63373) and natural (UPCB 63376; UPCB 63377; UPCB 63378) substrates.

Encyonopsis schubartii (Hustedt) Krammer

Figure: 3E

Length: 29.5-33.6 µm; width: 6-6.4 µm; dorsal striae: 9-11 in 10 µm; ventral striae: 9-12 in 10 µm.

Ecology: previously registered for oligotrophic (Krammer 1997bKRAMMER, K. 1997b. Die cymbelloidean Diatomeen: eine Monographie der weltweit bekannten taxa. II Encyonema part., Encyonopsis and Cymbellopsis. Biblioth. Diatomol. 37: 1-469. Verlag KG, Ruggell, v. 3, 584 p.), and mesotrophic environments, with acid pH (Wengrat et al. 2015WENGRAT, S., MARQUARDT, G.C., BICUDO, D.C., BICUDO, C.E.M., WETZEL, C.E. & ECTOR, L. 2015. Type analisys of Cymbella schubartii and two new Encyonopsis species (Bacillariophyceae) from southeastern Brazil. Phytotaxa 221(3): 247-264. http://dx.doi.org/10.11646/phytotaxa.221.3.3
http://dx.doi.org/10.11646/phytotaxa.221...
). In our samples, it occurred in circumneutral pH (6.7-6.85), low conductivity (22.5-24.5 µS cm-1) and oligotrophic conditions.

Occurrence in samples: artificial (UPCB 63371; UPCB 63372; UPCB 63373) and natural (UPCB 63375; UPCB 63377) substrates.

Encyonopsis subminuta Krammer & Reichardt.

Figure: 3F

Length: 15.3-21.3 µm; width: 3.7-4.8 µm; striae: 26 in 10 µm.

Ecology: common in oligo- and mesotrophic environments, and rare in electrolyte-poor environments (Bertolli et al. 2010BERTOLLI, L.M., TREMARIN, P.I. & LUDWIG, T.A.V. 2010. Diatomáceas perifíticas em Polygonum hydropiperoides Michaux, reservatório do Passaúna, Região Metropolitana de Curitiba, Paraná, Brasil. Acta Bot. Bras. 24(4):1065-1081. http://dx.doi.org/10.1590/S0102-33062010000400022
http://dx.doi.org/10.1590/S0102-33062010...
, Cantonati et al. 2017CANTONATI, M., KELLY, M.G. & LANGE-BERTALOT, H. 2017. Freshwater benthic diatoms of Central Europe: over 800 common species used in ecological assessment. English edition with update taxonomy and added species. Schmitten-Oberreifenberg: Koeltz Botanical Books. p. 1-942.). In our samples, it occurred in circumneutral pH (6.85), low conductivity (24 µS cm-1) and oligotrophic conditions, only in spring (temperature 20.8ºC).

Occurrence in samples: artificial substrate (UPCB 63371).

Gomphonema gracile Ehrenberg

Figure: 3J-3K

Length: 28-43 µm; width: 5.8-7.2 µm; striae: 14-16 in 10 µm.

The Gomphonema gracile species-complex includes representatives with valves of diverse forms, sizes and measures. Gomphonema naviculoides Smith is very similar to G. gracile in the valve outline and striae density, but they differ in the width range, being of 4.2-9 µm in G. gracile and of 7.8-9.5 µm in G. naviculoides (Reichardt 2015aREICHARDT, E. 2015a. Gomphonema gracile Ehrenberg sensu stricto et sensu auct. (Bacillariophyceae): A taxonomic revision. Nova Hedwigia. 101(3-4): 367-393. http://dx.doi.org/10.1127/nova_hedwigia/2015/0275
http://dx.doi.org/10.1127/nova_hedwigia/...
).

Ecology: typical of environments with low conductivity and nutrients (Krammer & Lange-Bertalot 1986KRAMMER, K. & LANGE-BERTALOT, H. 1986. Bacillariophyceae: Naviculaceae. In Süsswasserflora von Mitteleuropa (H. Ettl, J. Gerloff, H. Heynig, D. Mollenhauer, eds). Gustav Fischer, Jena. v. 2, pars 1, 876 p.). It occurred in all our samples, in slightly acid to circumneutral pH (6-6.85), low conductivity (22.5-24.5 µS cm-1) and oligotrophic conditions.

Occurrence in samples: artificial (UPCB 63371; UPCB 63372; UPCB 63373; UPCB 63374) and natural (UPCB 63375; UPCB 63376; UPCB 63377; UPCB 63378) substrates.

Gomphonema lagenula Kützing

Figures: 3L-3M

Length: 17.2-21.7 µm; width: 4.5-4.8 µm; striae: 18-19 in 10 µm

Ecology: considered as tolerant (Hofmann 1994HOFMANN, G. 1994. Aufwuchs-Diatomeen in Seen und ihre Eignung als Indikatoren der Trophie. Biblioth. Diatomol. J. Cramer, Berlin - Stuttgart, 30.), this species is widely distributed in environments ranging from oligotrophic to hypereutrophic (Bertolli, et al. 2010BERTOLLI, L.M., TREMARIN, P.I. & LUDWIG, T.A.V. 2010. Diatomáceas perifíticas em Polygonum hydropiperoides Michaux, reservatório do Passaúna, Região Metropolitana de Curitiba, Paraná, Brasil. Acta Bot. Bras. 24(4):1065-1081. http://dx.doi.org/10.1590/S0102-33062010000400022
http://dx.doi.org/10.1590/S0102-33062010...
, Silva et al. 2010SILVA, A.M., TREMARIN, P.I., LUDWIG, T.A.V. & VERCELLINO, I.S. 2010. Diatomáceas perifíticas em um sistema eutrófico brasileiro (Reservatório do Iraí, estado do Paraná). Acta Botanica Brasilica . 24(4): 997-1016. http://dx.doi.org/10.1590/S0102-33062010000400015
http://dx.doi.org/10.1590/S0102-33062010...
, Faria et al. 2010FARIA, D.M., TREMARIN, P.I. & LUDWIG, T.A.V. 2010. Diatomáceas perifíticas da represa Itaqui, São José dos Pinhais, Paraná: Fragilariales, Eunotiales, Achnanthales, e Gomphonema Ehrenberg. Biota Neotropica 10(3): http://www.biotaneotropica.org.br/v10n3/pt/abstract?inventory+bn04110032010
http://www.biotaneotropica.org.br/v10n3/...
, Marra et al. 2016MARRA, R.C., TREMARIN, P.I., ALGARTE, V.M. & LUDWIG, T.A. 2016. Epiphytic diatoms (Diatomeae) from Piraquara II urban reservoir, Paraná state. Biotaneotropica 16(4): e20160200. http://dx.doi.org/10.1590/1676-0611-BN-2016-0200
http://dx.doi.org/10.1590/1676-0611-BN-2...
, Bartozek et al. 2018BARTOZEK, E.C.R., ZORZAL-ALMEIDA, S. & BICUDO, D.C. 2018. Surface sediment and phytoplankton diatoms across a trophic gradient in tropical reservoirs: new records for Brazil and São Paulo State. Hoehnea 45(1): 69-92. http://dx.doi.org/10.1590/2236-8906-51/2017
http://dx.doi.org/10.1590/2236-8906-51/2...
). In our samples, it occurred in slightly acid to circumneutral pH (6-6.7), low conductivity (22.5-24.5 µS cm-1) and oligotrophic conditions, in autumn and winter (temperature < 19ºC).

Occurrence in samples: natural substrates (UPCB 63377; UPCB 63378).

Gomphonema pantropicum Reichardt

Figure: 3N-3O

Length: 35.2-38 µm; width: 6-6.3 µm; striae: 10-11 in 10 µm.

Valves lanceolate, with constricted round apices. Spaced and convergent striae towards the middle part of the valves and parallel to the apices.

In Brazilian environments, Gomphonema pantropicum is often misidentified as Gomphonema subtile Ehrenberg (Osorio et al. 2017OSÓRIO, N.C., TREMARIN, P.I., LUDWIG, T.V. & RODRIGUES, L. 2017. Gomphonema Ehrenberg (Bacillariohyceae) in a lotic environment of the Upper Paraná River floodplain, Brazil. Acta Scientiarum. 39(2): 135-147. http://dx.doi.org/10.4025/actascibiolsci.v39i2.32134
http://dx.doi.org/10.4025/actascibiolsci...
, Marra et al. 2016MARRA, R.C., TREMARIN, P.I., ALGARTE, V.M. & LUDWIG, T.A. 2016. Epiphytic diatoms (Diatomeae) from Piraquara II urban reservoir, Paraná state. Biotaneotropica 16(4): e20160200. http://dx.doi.org/10.1590/1676-0611-BN-2016-0200
http://dx.doi.org/10.1590/1676-0611-BN-2...
, Marquardt & Bicudo 2014MARQUARDT, G.C. & BICUDO, C.E.M. 2014. Criptógamos do Parque Estadual das Fontes do Ipiranga, São Paulo, SP. Algas 36: Bacillariophyceae (Cymbellales). Hoehnea 41(2): 209-246. http://dx.doi.org/10.1590/S2236-89062014000200005
http://dx.doi.org/10.1590/S2236-89062014...
). Gomphonema subtile presents the valves with broadly capitate ends, a long and narrow "neck" and flatly-rounded apices (Reichardt 2015bREICHARDT, E. 2015b. Taxonomy and distribution of Gomphonema subtile Ehrenberg (Bacillariophyceae) and six related taxa. Fottea. 15(1): 27-38. http://dx.doi.org/10.5507/fot.2015.003
http://dx.doi.org/10.5507/fot.2015.003...
).

Ecology: distributed in South America and in tropical Africa, India, and Southeast Asia (Reichardt 2015bREICHARDT, E. 2015b. Taxonomy and distribution of Gomphonema subtile Ehrenberg (Bacillariophyceae) and six related taxa. Fottea. 15(1): 27-38. http://dx.doi.org/10.5507/fot.2015.003
http://dx.doi.org/10.5507/fot.2015.003...
); the ecology of this species is little known. In Brazil, it was previously registered from epiphytic samples in the North and South region (Medeiros et al. 2018MEDEIROS, G., AMARAL, M.W.W., FERREIRA, P.C., LUDWIG, T.A.V. & BUENO, N.C. 2018. Gomphonema Ehrenberg (Bacillariophyceae, Gomphonemataceae) of the São Francisco Falso River, Paraná, Brazil. Biota Neotropica 18(3): e20170495. http://dx.doi.org/10.1590/1676-0611-BN-2017-0495
http://dx.doi.org/10.1590/1676-0611-BN-2...
, Azevedo et al. 2018AZEVEDO, J.S., TALGATTI, D.M., TORGAN, L.C., PEREIRA, A.C. & MELO, S. 2018. O genero Gomphonema (Bacillariophyta) na comunidade perifítica do rio e reservatório de Curuá-Una (Santarém, Pará, Brasil). Rodriguésia 69(2): 765-776. http://dx.doi.org/10.1590/2175-7860201869234
http://dx.doi.org/10.1590/2175-786020186...
). In our samples, it occurred in slightly acid pH (6), low conductivity (24.5 µS cm-1) and oligotrophic conditions, only in winter (temperature 16ºC).

Occurrence in samples: artificial substrates (UPCB 63374).

Gomphonema spiculoides Gandhi

Figures: 3G-3I

Length: 54.2-69 µm; width: 7.3-8 µm; striae: 14 in 10 µm.

This species presents valve ends clearly apiculate, a central area weakly delimited, a narrow axial area, undulate and lateral raphe, and striae slightly radiate.

The specimens recorded in the present study have striae slightly radiate and a less width than the specimens found by Karthick & Kociolek (2012)KARTHICK, B. & KOCIOLEK, P. 2012. Reconsideration of the Gomphonema (Bacillariophyceae) species from Kholhapur, Northern Western Ghats, India: Taxonomy, typification and biogeography of the species reported by H. P. Gandhi. Phycological Research 60: 179-198. http://dx.doi.org/10.1111/j.1440-1835.2012.00649.x
http://dx.doi.org/10.1111/j.1440-1835.20...
, resembling the Gandhi's original draw and description. Gomphonema spiculoides can be mistaken with large valves of Gomphonema gracile Ehrenberg.

Ecology: this species has a low tolerance to alkaline conditions and it was previously registered for oligotrophic and slightly acid waters (Riato et al. 2017RIATO, L., LEIRA, M., DELLA BELLA, V. & OBERHOLSTER, P.J. 2017. Diatom-based models for inferring water chemistry and hydrology in temporary depressional wetlands. Hydrobiologia 797: 127-143. http://dx.doi.org/10.1007/s10750-017-3165-8
http://dx.doi.org/10.1007/s10750-017-316...
). It occurred in all our samples, in slightly acid to circumneutral pH (6-6.85), low conductivity (22.5-24.5 µS cm-1) and oligotrophic conditions.

This is the first record for Brazil.

Occurrence in samples: artificial (UPCB 63371; UPCB 63372; UPCB 63373; UPCB 63374) and natural (UPCB 63375; UPCB 63376; UPCB 63377; UPCB 63378) substrates.

Family CYMBELLACEAE

Cymbopleura naviculiformis (Auerswald) Krammer

Figure: 3P

Length: 32.1 µm; width: 9 µm; dorsal striae: 13 in 10 µm; ventral striae: 15 in 10 µm.

Ecology: previously registered for oligotrophic to eutrophic waters (Bertolli et al. 2010BERTOLLI, L.M., TREMARIN, P.I. & LUDWIG, T.A.V. 2010. Diatomáceas perifíticas em Polygonum hydropiperoides Michaux, reservatório do Passaúna, Região Metropolitana de Curitiba, Paraná, Brasil. Acta Bot. Bras. 24(4):1065-1081. http://dx.doi.org/10.1590/S0102-33062010000400022
http://dx.doi.org/10.1590/S0102-33062010...
, Silva et al. 2010SILVA, A.M., TREMARIN, P.I., LUDWIG, T.A.V. & VERCELLINO, I.S. 2010. Diatomáceas perifíticas em um sistema eutrófico brasileiro (Reservatório do Iraí, estado do Paraná). Acta Botanica Brasilica . 24(4): 997-1016. http://dx.doi.org/10.1590/S0102-33062010000400015
http://dx.doi.org/10.1590/S0102-33062010...
, Marra et al. 2016MARRA, R.C., TREMARIN, P.I., ALGARTE, V.M. & LUDWIG, T.A. 2016. Epiphytic diatoms (Diatomeae) from Piraquara II urban reservoir, Paraná state. Biotaneotropica 16(4): e20160200. http://dx.doi.org/10.1590/1676-0611-BN-2016-0200
http://dx.doi.org/10.1590/1676-0611-BN-2...
, Cantonati et al. 2017CANTONATI, M., KELLY, M.G. & LANGE-BERTALOT, H. 2017. Freshwater benthic diatoms of Central Europe: over 800 common species used in ecological assessment. English edition with update taxonomy and added species. Schmitten-Oberreifenberg: Koeltz Botanical Books. p. 1-942.). In our samples, it occurred in circumneutral pH (6.85), low conductivity (24 µS cm-1) and oligotrophic conditions, only in spring (temperature 20.8ºC).

Occurrence in samples: natural substrates (UPCB 63375).

Family ACHNANTHIDIACEAE

Achnanthidium minutissimum (Kützing) Czarnecki

Figures: 3T-3W

Length: 9.6-15.4 µm; width: 2.6-2.8 µm; indistinct striae.

Ecology: very wide range of ecological preferences (Cantonati et al. 2017CANTONATI, M., KELLY, M.G. & LANGE-BERTALOT, H. 2017. Freshwater benthic diatoms of Central Europe: over 800 common species used in ecological assessment. English edition with update taxonomy and added species. Schmitten-Oberreifenberg: Koeltz Botanical Books. p. 1-942.). In our samples, it occurred in temperature < 21ºC, slightly acid to circumneutral pH (6-6.85), low conductivity (22.5-24.5 µS cm-1) and oligotrophic conditions.

Occurrence in samples: artificial (UPCB 63371; UPCB 63374) and natural (UPCB 63375; UPCB 63377; UPCB 63378) substrates.

Achnanthidium neomicrocephalum Lange-Bertalot & Staab

Figures: 3X-3AD

Length: 21.6-25.3 µm; width: 2.5-2.8 µm; indistinct striae.

Valves linear-lanceolate with subcapitate apices. Axial area narrow. Central area variable in shape.

Achnanthidium neomicrocephalum has narrower valves than Achnanthidium gracillimum (Meister) Lange-Bertalot (3.4-4.5 µm) and A. caledonicum (Lange-Bertalot) Lange-Bertalot (2.7-3.8 µm). Achnanthidium caledonicum presents broader valve ends than A. neomicrocephalum.

Ecology: previously registered for oligotrophic environments, mainly springs and lakes (Cantonati et al. 2017CANTONATI, M., KELLY, M.G. & LANGE-BERTALOT, H. 2017. Freshwater benthic diatoms of Central Europe: over 800 common species used in ecological assessment. English edition with update taxonomy and added species. Schmitten-Oberreifenberg: Koeltz Botanical Books. p. 1-942., Cantonati & Lange-Bertalot 2010CANTONATI, M. & LANGE-BERTALOT, H. 2010. Diatom biodiversity of springs in the Berchtesgaden National Park (North-Eastern Alps, Germany), with the ecological and morphological characterization of two species new to science. Diat. Res. 25(2): 251-280. http://dx.doi.org/10.1080/0269249X.2010.9705849
http://dx.doi.org/10.1080/0269249X.2010....
). In our samples, it occurred in slightly acid pH (6) and low conductivity (24.5 µS cm-1), and oligotrophic condition, only in winter (temperature 16ºC).

This is the first record for Brazil

Occurrence in samples: artificial substrates (UPCB 63374).

Achnanthidium sp.

Figures: 3AE-3AH

Length: 13.3-15.4 µm; width: 2.4-2.5 µm; indistinct striae.

Valves linear-lanceolate, with parallel margins and capitate apices. Narrow and linear axial area. Central area bordered by one striae on both sides. Resembles Achnanthidium tropicocatenatum Marquardt, Wetzel & Ector although the central portion is not inflated (Marquard et al. 2017MARQUARDT, G.C., BICUDO, C.E.M., LUDWIG, T.A.V., ECTOR, L. & WETZEL, C.E. 2018. Diatom assemblages (Bacillariophyta)in six tropical reservoirs from southeast Brazil: species composition and spatial and temporal variation patterns. Acta Limnologica Brasiliensia 30: e201. https://doi.org/10.1590/S2179-975X6417
https://doi.org/10.1590/S2179-975X6417...
).

Ecology: this species was frequent in ours samples, and occurred in slightly acid to circumneutral pH (6-6.85), low conductivity (22.5-24.5 µS cm-1) and oligotrophic conditions.

Occurrence in samples: artificial (UPCB 63371; UPCB 63373) and natural (UPCB 63375; UPCB 63376; UPCB 63377; UPCB 63378) substrates.

Planothidium incuriatum Wetzel, Van de Vijver & Ector

Figures: 3AI-3AJ

Length: 20 µm; width: 7 µm; striae: 14 in 10 µm.

Planothidium incuriatum is widely reported in Brazil as P. biporomum (Hohn & Hellerman) Lange-Bertalot, characterized by the rostrate apices that differ from the capitate to subcapitate apices of P. biporomum. Planothidium incuriatum is also misidentified as P. rostratum (Østrup) Round & Bukhtiyarova but it can be distinguished by its smaller dimensions (Wetzel et al. 2013WETZEL, C.E., VAN DE VIJVER, B., HOFFMANN, L. & ECTOR, L. 2013. Planothidium incuriatumsp. nov. a widely distributed diatom species (Bacillariophyta) and type analysis of Planothidium biporomum. Phytotaxa. 138(1): 43-57. http://dx.doi.org/10.11646/phytotaxa.138.1.6
http://dx.doi.org/10.11646/phytotaxa.138...
).

Ecology: widely distributed in a broad range of environmental conditions (Wetzel et al. 2013WETZEL, C.E., VAN DE VIJVER, B., HOFFMANN, L. & ECTOR, L. 2013. Planothidium incuriatumsp. nov. a widely distributed diatom species (Bacillariophyta) and type analysis of Planothidium biporomum. Phytotaxa. 138(1): 43-57. http://dx.doi.org/10.11646/phytotaxa.138.1.6
http://dx.doi.org/10.11646/phytotaxa.138...
). In our samples, it occurred in circumneutral pH (6.85), low conductivity (24 µS cm-1) and oligotrophic conditions, only in spring (temperature 20.8ºC).

Occurrence in samples: natural substrates (UPCB 63375).

Family DIADESMIDACEAE

Humidophila biscutella (Moser, Lange-Bertalot & Mezeltin) Lowe, Kociolek, Johansen, Van de Vijver, Lange-Bertalot & Kopalová

Figure: 3AK

Length: 9.5 µm; width: 2.3 µm; indistinct striae.

Valves linear with concave margins and broadly rounded apices; the central area is elliptical and not forming fascia. It is possible that Humidophila biscutella has been previously reported as Humidophila contenta (Grunow) Lowe, Kociolek, Johansen, Van de Vijver, Lange-Bertalot & Kopalová. It differs from the latter species by the absence of wide apices and of the central area with fascia (Moser et al. 1998MOSER, G. , LANGE-BERTALOT, H. & METZELTIN, D. 1998. Insel der Endemiten Geobotanisches Phänomen Neukaledonien (Island of endemics New Caledonia - a geobotanical phenomenon). Bibliotheca Diatomologica 38:464 pp.). Humidophila deceptionensis Kopalová, Zidarova & Van de Vijver is similar to H. biscutella, but has wider valves (2.7-3.2 µm) (Kopalová et al. 2015KOPALOVÁ, K., KOCIOLEK, J.P., LOWE, R.L., ZIDAROVA, R. & VAN DE VIJVER, B. 2015. Five new species of the genus Humidophila (Bacillariophyta) from the Maritime Antarctic Region. Diatom Research 30(2): 117-131. http://dx.doi.org/10.1080/0269249X.2014.998714
http://dx.doi.org/10.1080/0269249X.2014....
). In Brazil, it was previously registered for reservoirs in São Paulo state (Marquardt et al. 2018MEDEIROS, G., AMARAL, M.W.W., FERREIRA, P.C., LUDWIG, T.A.V. & BUENO, N.C. 2018. Gomphonema Ehrenberg (Bacillariophyceae, Gomphonemataceae) of the São Francisco Falso River, Paraná, Brazil. Biota Neotropica 18(3): e20170495. http://dx.doi.org/10.1590/1676-0611-BN-2017-0495
http://dx.doi.org/10.1590/1676-0611-BN-2...
).

Ecology: the ecology of this species id little known. In our samples, it occurred only in temperatures < 19ºC, slightly acid to circumneutral pH (6-6.75), low conductivity (22.5-24.5 µS cm-1) and oligotrophic conditions.

This is the first record for Paraná state.

Occurrence in samples: artificial (UPCB 63373; UPCB 63374) and natural (UPCB 63378) substrates.

Luticola permuticoides Metzeltin & Lange-Bertalot

Figure: 3AL

Length: 13.5-19.1 µm; width: 6.4-7.8 µm; striae: 19 in 10 µm.

Ecology: found in epiphytic samples collected in rivers with slightly acidic waters (Straube et al. 2017STRAUBE, A., TREMARIN, P.I. & LUDWIG, T.A.V. 2017. Species of Luticola D. G. Mann (Bacillariophyceae) in the Atlantic Forest rivers from southern Brazil. Diatom Research 32(4): 417-437. http://dx.doi.org/10.1080/0269249X.2017.1389771
http://dx.doi.org/10.1080/0269249X.2017....
). In our samples, it occurred in slightly acid pH (6), low conductivity (24.5 µS cm-1) and oligotrophic conditions, only in winter (temperature 16ºC).

Occurrence in samples: natural substrates (UPCB 63378).

Luticola simplex Metzeltin, Lange-Bertalot & García-Rodríguez

Figure: 3AM

Length: 12.8-16 µm; width: 4.8-5 µm; striae: 24 in 10 µm.

Ecology: previously recorded from sediment samples of subfossil assemblages in oligotrophic conditions and from modern assemblages in eutrophic conditions (Faustino et al. 2016FAUSTINO, S.B., FONTANA, L., BARTOZEK, E.C.R., BICUDO, C.E.M. & BICUDO, D.C. 2016. Composition and distribution of diatom assemblages from core and surface sediments of a water supply reservoir in Southeastern Brazil. Biota Neotropica: 16(2): e20150129. http://dx.doi.org/10.1590/1676-0611-BN-2015-0129
http://dx.doi.org/10.1590/1676-0611-BN-2...
). In our samples, it occurred in circumneutral pH (6.75), low conductivity (24.5 µS cm-1) and oligotrophic conditions, only in summer (temperature of 27ºC and accumulated rainfall of 326.9 mm).

Occurrence in samples: natural substrates (UPCB 63376).

Family AMPHIPLEURACEAE

Frustulia australocrassinervia Casa, Mataloni & Van de Vijver

Figures: 3AN-3AP

Length: 32-43.2 µm; width: 8-9.6 µm; delicate striae, ratio 3.8-4.6.

This taxon has lanceolate valves, with slightly triundulate margins, protracted and rostrate apices. It differs from Frustulia crassinervia (Brébisson) Lange-Bertalot & Krammer by the presence of wider valves (11.5-12.5 µm) (Casa et al. 2018CASA, V., MATALONI, G. & VAN DE VIJVER, B. 2018. Six new Frustulia species (Bacillariophyta) in Tierra del Fuego peatbogs, Patagonia, Argentina. Fottea. 18(1): 55-71. http://dx.doi.org/10.5507/fot.2017.016
http://dx.doi.org/10.5507/fot.2017.016...
).

Ecology: previously registered for acidic waters with low conductivity (Casa et al. 2018CASA, V., MATALONI, G. & VAN DE VIJVER, B. 2018. Six new Frustulia species (Bacillariophyta) in Tierra del Fuego peatbogs, Patagonia, Argentina. Fottea. 18(1): 55-71. http://dx.doi.org/10.5507/fot.2017.016
http://dx.doi.org/10.5507/fot.2017.016...
). It occurred in all samples, in slightly acid to circumneutral pH (6-6.85), low conductivity (22.5-24.5 µS cm-1) and oligotrophic conditions.

This is the first record for Brazil.

Occurrence in samples: artificial (UPCB 63371; UPCB 63372; UPCB 63373; UPCB 63374) and natural (UPCB 63375; UPCB 63376; UPCB 63377; UPCB 63378) substrates.

Frustulia undosa Metzeltin & Lange-Bertalot

Figures: 3AQ-3AS

Length: 24.5-44.1 µm; width: 7.5-10 µm; delicate striae.

It differs from Frustulia crassinervia (Brébisson) Lange-Bertalot & Krammer by the presence of a narrower and longer tri-undulated valve (Metzeltin & Lange-Bertalot 1998METZELTIN, D. & LANGE-BERTALOT, H. 1998. Tropical diatoms of South America I. About 700 predominantly rarely known or new taxa representative of the neotropical flora. In Iconogr. Diatomol. (H. Lange-Bertalot , ed.) 5: 1-695.).

Ecology: previously registered for a mesotrophic reservoir (Marra et al. 2016MARRA, R.C., TREMARIN, P.I., ALGARTE, V.M. & LUDWIG, T.A. 2016. Epiphytic diatoms (Diatomeae) from Piraquara II urban reservoir, Paraná state. Biotaneotropica 16(4): e20160200. http://dx.doi.org/10.1590/1676-0611-BN-2016-0200
http://dx.doi.org/10.1590/1676-0611-BN-2...
). In our samples, it occurred in slightly acid to circumneutral pH (6-6.75), low conductivity (22.5-24.5 µS cm-1) and oligotrophic conditions.

Occurrence in samples: artificial (UPCB 63373; UPCB 63374) and natural (UPCB 63376; UPCB 63377) substrates.

Family BRACHYSIRACEAE

Brachysira neoexilis Lange-Bertalot

Figures: 3AT-3AV

Length: 16-32 µm; width: 4-5.6 µm; striae: difficult to distinguish

Wolfe & Kling (2001)WOLFE, A.P. & KLING, H.J. 2015. A consideration of some North American soft-water Brachysira taxa and description of B. arctoborealis sp. nov. Studies on Diatoms. 243-264. have suggested that Brachysira neoexilis is a synonym of Brachysira microcephala (Grunow) Compère. Some authors consider that both species differ significantly (Cantonati et al. 2017CANTONATI, M., KELLY, M.G. & LANGE-BERTALOT, H. 2017. Freshwater benthic diatoms of Central Europe: over 800 common species used in ecological assessment. English edition with update taxonomy and added species. Schmitten-Oberreifenberg: Koeltz Botanical Books. p. 1-942.) since the latter species presents clearly capitate apices and usually wider valves than B. neoexilis.

Ecology: considered as a species distributed in oligotrophic and acidic conditions (Lange-Bertalot & Moser 1994LANGE-BERTALOT, H. & MOSER, G. 1994. Brachysira Monographie der Gattung. Wichtige Indikator Species für das Gewässermonitoring und Naviculadicta nov. gen. Biblio. Diatomol. 29: 1-212., Cantonati et al. 2017CANTONATI, M., KELLY, M.G. & LANGE-BERTALOT, H. 2017. Freshwater benthic diatoms of Central Europe: over 800 common species used in ecological assessment. English edition with update taxonomy and added species. Schmitten-Oberreifenberg: Koeltz Botanical Books. p. 1-942.), and previously registered for mesotrophic and eutrophic reservoirs (Bertolli et al. 2010BERTOLLI, L.M., TREMARIN, P.I. & LUDWIG, T.A.V. 2010. Diatomáceas perifíticas em Polygonum hydropiperoides Michaux, reservatório do Passaúna, Região Metropolitana de Curitiba, Paraná, Brasil. Acta Bot. Bras. 24(4):1065-1081. http://dx.doi.org/10.1590/S0102-33062010000400022
http://dx.doi.org/10.1590/S0102-33062010...
, Silva et al. 2010SILVA, A.M., TREMARIN, P.I., LUDWIG, T.A.V. & VERCELLINO, I.S. 2010. Diatomáceas perifíticas em um sistema eutrófico brasileiro (Reservatório do Iraí, estado do Paraná). Acta Botanica Brasilica . 24(4): 997-1016. http://dx.doi.org/10.1590/S0102-33062010000400015
http://dx.doi.org/10.1590/S0102-33062010...
, Marra et al. 2016MARRA, R.C., TREMARIN, P.I., ALGARTE, V.M. & LUDWIG, T.A. 2016. Epiphytic diatoms (Diatomeae) from Piraquara II urban reservoir, Paraná state. Biotaneotropica 16(4): e20160200. http://dx.doi.org/10.1590/1676-0611-BN-2016-0200
http://dx.doi.org/10.1590/1676-0611-BN-2...
). It occurred in all our samples, in slightly acid to circumneutral pH (6-6.85), low conductivity (22.5-24.5 µS cm-1) and oligotrophic conditions.

Occurrence in samples: artificial (UPCB 63371; UPCB 63372; UPCB 63373; UPCB 63374) and natural (UPCB 63375; UPCB 63376; UPCB 63377; UPCB 63378) substrates.

Family NEIDIACEAE

Neidium affine (Ehrenberg) Pfitzer

Figures: 3AW-3AX

Length: 42.9-46.1 µm; width: 10-10.8 µm; striae 25-26 in 10 µm.

Ecology: previously registered for oligotrophic and mesotrophic environments (Hofmann 1994HOFMANN, G. 1994. Aufwuchs-Diatomeen in Seen und ihre Eignung als Indikatoren der Trophie. Biblioth. Diatomol. J. Cramer, Berlin - Stuttgart, 30., Marra et al. 2016MARRA, R.C., TREMARIN, P.I., ALGARTE, V.M. & LUDWIG, T.A. 2016. Epiphytic diatoms (Diatomeae) from Piraquara II urban reservoir, Paraná state. Biotaneotropica 16(4): e20160200. http://dx.doi.org/10.1590/1676-0611-BN-2016-0200
http://dx.doi.org/10.1590/1676-0611-BN-2...
). In our samples, it occurred in circumneutral pH (6.7), low conductivity (22.5 µS cm-1) and oligotrophic conditions, only in autumn (temperature of 18.6ºC).

Occurrence in samples: natural substrates (UPCB 63377).

Family SELLAPHORACEAE

Sellaphora rectangularis (Gregory) Lange-Bertalot & Metzeltin

Figure: 4C

Figure 4
A–B. Sellaphora tridentula; C. Sellaphora rectangularis; D. Pinnularia borealis; E. Pinnularia brauniana; F. Pinnularia divergens var. divergens; G. Pinnularia divergens var. media; H. Pinnularia grunowii; I–J. Pinnularia obscura; K. Pinnularia pseudogibba; L–M. Hantzschia amphioxys; N. Pinnularia schoenfelderi; O. Kobayasiella sp.; P–Q. Capartogramma crucicula; R–T. Nitzschia semirobusta; U–V. Nitzschia acidoclinata; W. Nitzschia nana; X. Pinnularia viridiformis var. viridiformis; Y. Pinnularia viridiformis var. minor; Z. Pinnularia rumrichiae; AA. Pinnularia subcapitata var. elongata; AB. Pinnularia subcapitata var. subrostrata; AC–AD. Pinnularia subgibba var. undulata; AE. Pinnularia submicrostauron; AF. Navicula cryptocephala; AG. Navicula cryptotenella; AH. Navicula leptostriata; AI. Navicula veneta; AJ–AK. Chammaepinularia brasilianopsis; AL–AP. Chammaepinnularia mediocris.

Length: 31.3-48.8 µm; width: 7.1-11.7 µm; striae: 21-27 in 10 µm.

Ecology: previously registered for oligotrophic to eutrophic environments (van Dam et al. 1994VAN DAM, H., MERTENS, A. & SINKELDAM, J. 1994. A coded checklist and ecological indicator values of freshwater diatoms from the Netherlands. Neth. J. Aquatic Ecol. 28(1): 117-133. http://dx.doi.org/10.1007/BF02334251
http://dx.doi.org/10.1007/BF02334251...
, Lange-Bertalot & Metzeltin 1996LANGE-BERTALOT, H. & METZELTIN, D. 1996. Indicators of oligotrophy-800 taxa representative of three ecologically distinct lake types, Carbonate buffered-Oligodystrophic-Weakly buffered soft water. In Iconogr. Diatomol. (H. Lange-Bertalot, ed.). Gantner Verlag KG, Ruggell, 2:1-390.). In our samples, it occurred in autumn and winter samples (temperature < 19ºC). Thys study extends its occurrence to slightly acid to circumneutral pH (6-6.7), and low conductivity (22.5-24.5 µS cm-1) conditions.

Occurrence in samples: artificial (UPCB 63373; UPCB 63374) and natural (UPCB 63377) substrates.

Sellaphora tridentula (Krasske) C.E.Wetzel

Figure: 4A-4B

Length: 17.5-20.8 µm; width: 4-4.6 µm; striae: difficult to distinguish.

Ecology: considered as an acidophile species (van Dam et al. 1994VAN DAM, H., MERTENS, A. & SINKELDAM, J. 1994. A coded checklist and ecological indicator values of freshwater diatoms from the Netherlands. Neth. J. Aquatic Ecol. 28(1): 117-133. http://dx.doi.org/10.1007/BF02334251
http://dx.doi.org/10.1007/BF02334251...
). In our samples, it occurred in spring and autumn (temperature < 21ºC). This study extends the occurrence of this species to circumneutral pH (6.7-6.85), low conductivity (22.5-24 µS cm-1) and oligotrophic conditions.

Occurrence in samples: natural substrates (UPCB 63375; UPCB 63377).

Family PINNULARIACEAE

Pinnularia borealis Ehrenberg var. borealis.

Figure: 4D

Length: 31-31.2 µm; width: 7-7.2 µm; striae: 7 in 10 µm.

Ecology: considered as indifferent to environmental conditions (Hofmann 1994HOFMANN, G. 1994. Aufwuchs-Diatomeen in Seen und ihre Eignung als Indikatoren der Trophie. Biblioth. Diatomol. J. Cramer, Berlin - Stuttgart, 30.) P. borealis is common in oligo and mesotrophic environments (van Dam et al. 1994VAN DAM, H., MERTENS, A. & SINKELDAM, J. 1994. A coded checklist and ecological indicator values of freshwater diatoms from the Netherlands. Neth. J. Aquatic Ecol. 28(1): 117-133. http://dx.doi.org/10.1007/BF02334251
http://dx.doi.org/10.1007/BF02334251...
, Bertolii et al. 2010BERTOLLI, L.M., TREMARIN, P.I. & LUDWIG, T.A.V. 2010. Diatomáceas perifíticas em Polygonum hydropiperoides Michaux, reservatório do Passaúna, Região Metropolitana de Curitiba, Paraná, Brasil. Acta Bot. Bras. 24(4):1065-1081. http://dx.doi.org/10.1590/S0102-33062010000400022
http://dx.doi.org/10.1590/S0102-33062010...
), while rarely registered for eutrophic conditions (Silva et al. 2010SILVA, A.M., TREMARIN, P.I., LUDWIG, T.A.V. & VERCELLINO, I.S. 2010. Diatomáceas perifíticas em um sistema eutrófico brasileiro (Reservatório do Iraí, estado do Paraná). Acta Botanica Brasilica . 24(4): 997-1016. http://dx.doi.org/10.1590/S0102-33062010000400015
http://dx.doi.org/10.1590/S0102-33062010...
). In our samples, it occurred in temperature s < 21ºC, slightly acid to circumneutral pH (6-6.85), low conductivity (24-24.5 µS cm-1) and in oligotrophic conditions.

Occurrence in samples: artificial (UPCB 63374) and natural (UPCB 63375) substrates.

Pinnularia brauniana (Grunow) Studnicka.

Figure: 4E

Length: 52.2-60 µm; width: 8.5-9.6 µm; striae: 11-12 in 10 µm.

Ecology: previously registered for oligotrophic, mesotrophic and eutrophic conditions (Van Dam et al. 1994, Silva et al. 2010SILVA, A.M., TREMARIN, P.I., LUDWIG, T.A.V. & VERCELLINO, I.S. 2010. Diatomáceas perifíticas em um sistema eutrófico brasileiro (Reservatório do Iraí, estado do Paraná). Acta Botanica Brasilica . 24(4): 997-1016. http://dx.doi.org/10.1590/S0102-33062010000400015
http://dx.doi.org/10.1590/S0102-33062010...
, Marra et al. 2016MARRA, R.C., TREMARIN, P.I., ALGARTE, V.M. & LUDWIG, T.A. 2016. Epiphytic diatoms (Diatomeae) from Piraquara II urban reservoir, Paraná state. Biotaneotropica 16(4): e20160200. http://dx.doi.org/10.1590/1676-0611-BN-2016-0200
http://dx.doi.org/10.1590/1676-0611-BN-2...
). According to Krammer (1992)KRAMMER, K. 1992. Pinnularia, eine Monographie der europäischen Taxa. Bibliotheca Diatomologica, Stuttgart, 26., P. brauniana is not considered commonly found in waters with low conductivity and pH < 6. This study extends its occurrence to temperatures < 21ºC, acid to circumneutral pH (6-6.85), low conductivity (22.5-24.5 µS cm-1), and oligotrophic conditions.

Occurrence in samples: artificial (UPCB 63371; UPCB 63373; UPCB 63374) and natural (UPCB 63375; UPCB 63377; UPCB 63378) substrates.

Pinnularia divergens Smith var. divergens

Figure: 4F

Length: 74.5 µm; width: 12.5 µm; striae: 12 in 10 µm.

Ecology: in agreement with previously studies (van Dam et al. 1994VAN DAM, H., MERTENS, A. & SINKELDAM, J. 1994. A coded checklist and ecological indicator values of freshwater diatoms from the Netherlands. Neth. J. Aquatic Ecol. 28(1): 117-133. http://dx.doi.org/10.1007/BF02334251
http://dx.doi.org/10.1007/BF02334251...
, Cantonati et al. 2017CANTONATI, M., KELLY, M.G. & LANGE-BERTALOT, H. 2017. Freshwater benthic diatoms of Central Europe: over 800 common species used in ecological assessment. English edition with update taxonomy and added species. Schmitten-Oberreifenberg: Koeltz Botanical Books. p. 1-942.), we found this species in pH < 7, low conductivity (22.5 µS cm-1) and oligotrophic conditions only in autumn (temperature 18.6ºC).

Occurrence in samples: natural substrates (UPCB 63377).

Pinnularia divergens var. media Krammer

Figure: 4G

Length: 39-54.5 µm; width: 7.7-9.5 µm; striae: 14-15 in 10 µm.

Ecology: according to previous studies, this species prefers oligotrophic environments (van Dam et al. 1994VAN DAM, H., MERTENS, A. & SINKELDAM, J. 1994. A coded checklist and ecological indicator values of freshwater diatoms from the Netherlands. Neth. J. Aquatic Ecol. 28(1): 117-133. http://dx.doi.org/10.1007/BF02334251
http://dx.doi.org/10.1007/BF02334251...
, Cantonati et al. 2017CANTONATI, M., KELLY, M.G. & LANGE-BERTALOT, H. 2017. Freshwater benthic diatoms of Central Europe: over 800 common species used in ecological assessment. English edition with update taxonomy and added species. Schmitten-Oberreifenberg: Koeltz Botanical Books. p. 1-942.) but can also occur in eutrophic waters (Silva et al. 2010SILVA, A.M., TREMARIN, P.I., LUDWIG, T.A.V. & VERCELLINO, I.S. 2010. Diatomáceas perifíticas em um sistema eutrófico brasileiro (Reservatório do Iraí, estado do Paraná). Acta Botanica Brasilica . 24(4): 997-1016. http://dx.doi.org/10.1590/S0102-33062010000400015
http://dx.doi.org/10.1590/S0102-33062010...
). In our samples, it occurred in in temperatures < 21ºC, slightly acid to circumneutral pH (6-6.85), low conductivity (24-24.5 µS cm-1) and in oligotrophic conditions.

Occurrence in samples: natural substrates (UPCB 63375; UPCB 63377; UPCB 63378).

Pinnularia grunowii Krammer

Figure: 4H

Length: 31-41 µm; width: 6-7.5 µm; striae: 14 in 10 µm.

Ecology: previously registered for eutrophic environments, with low to moderate electrolytes and pH > 8 (Krammer 2000KRAMMER, K. 2000. The genus Pinnularia. In Diatoms of Europe 1 (H. Lange-Bertalot) p. 1-703.) and also for mesotrophic waters (Bertolli et al. 2010BERTOLLI, L.M., TREMARIN, P.I. & LUDWIG, T.A.V. 2010. Diatomáceas perifíticas em Polygonum hydropiperoides Michaux, reservatório do Passaúna, Região Metropolitana de Curitiba, Paraná, Brasil. Acta Bot. Bras. 24(4):1065-1081. http://dx.doi.org/10.1590/S0102-33062010000400022
http://dx.doi.org/10.1590/S0102-33062010...
). In our samples, it occurred in circumneutral pH (6.7-6.85) and low conductivity (22.5-24.5 µS cm-1), and oligotrophic conditions.

Occurrence in samples: artificial (UPCB 63373) and natural (UPCB 63375; UPCB 63376) substrates.

Pinnularia obscura Krasske

Figures: 4I-4J

Length: 20.5-21.5 µm; width: 4-4.5 µm; striae: 16 in 10 µm.

Ecology: considered as a species tolerant to environments with pH < 4 (Ciniglia et al. 2007CINIGLIA, C., CENNAMO, P., DE STEFANO, M., PINTO, G., CAPUTO, P. & POLLIO, A. 2007. Pinnularia obscura Krasske (Bacillariophyceae, Bacillariophyta) from acidic environments: characterization and comparison with other acid-tolerant Pinnularia species. Fundamental and Applied Limnology Archiv für Hydrobiologie 170(1): 29-47. http://dx.doi.org/10.1127/1863-9135/2007/0170-0029
http://dx.doi.org/10.1127/1863-9135/2007...
). In our samples, it occurred in circumneutral pH (6.7-6.85), low conductivity (22.5-24 µS cm-1), and oligotrophic conditions, in spring and autumn (temperature < 21ºC).

Occurrence in samples: natural substrates (UPCB 63375; UPCB 63377).

Pinnularia pseudogibba Krammer

Figure: 4K

Length: 54 µm; width: 9 µm; striae: 11 in 10 µm.

Pinnularia pseudogibba differs from Pinnularia subgibba Krammer var. subgibba by the presence of lanceolate valves with subrostrate apices (Krammer 2000KRAMMER, K. 2000. The genus Pinnularia. In Diatoms of Europe 1 (H. Lange-Bertalot) p. 1-703.).

Ecology: previously registered for oligotrophic environments (Krammer 2000KRAMMER, K. 2000. The genus Pinnularia. In Diatoms of Europe 1 (H. Lange-Bertalot) p. 1-703.). In our samples, it occurred in slightly acid to circumneutral pH (6-6.85), low conductivity (24-24.5 µS cm-1) and oligotrophic conditions.

Occurrence in samples: artificial (UPCB 63371; UPCB 63374) and natural (UPCB 63375; UPCB 63376; UPCB 63377) substrates.

Pinnularia rumrichae Krammer.

Figure: 4Z

Length: 45-46.5 µm; width: 7.5-8 µm; striae: 13 in 10 µm.

Ecology: in our samples, it occurred in slightly acidic to circumneutral pH (6-6.85), low conductivity (24-24.5 µS cm-1) and in oligotrophic conditions.

Occurrence in samples: artificial (UPCB 63373) and natural (UPCB 63375; UPCB 63376; UPCB 63378) substrates.

Pinnularia schoenfelderi Krammer.

Figure: 4N

Length: 23 µm; width: 4.8 µm; striae: 16 in 10 µm.

Ecology: previously registered for oligotrophic environments with low to moderate conductivity (Krammer 2000KRAMMER, K. 2000. The genus Pinnularia. In Diatoms of Europe 1 (H. Lange-Bertalot) p. 1-703.), and also for mesotrophic waters (Bertollit et al. 2010BERTOLLI, L.M., TREMARIN, P.I. & LUDWIG, T.A.V. 2010. Diatomáceas perifíticas em Polygonum hydropiperoides Michaux, reservatório do Passaúna, Região Metropolitana de Curitiba, Paraná, Brasil. Acta Bot. Bras. 24(4):1065-1081. http://dx.doi.org/10.1590/S0102-33062010000400022
http://dx.doi.org/10.1590/S0102-33062010...
). In our samples, it occurred in circumneutral pH (6.7), low conductivity (22.5 µS cm-1) and oligotrophic conditions, only in autumn (temperature 18.6ºC).

Occurrence in samples: natural substrates (UPCB 63377).

Pinnularia subcapitata var. elongata Krammer.

Figure: 4AA

Length: 43.5 µm; width: 6 µm; striae: 16 in 10 µm.

Ecology: commonly associated with sphagnum moss (Krammer 1992KRAMMER, K. 1992. Pinnularia, eine Monographie der europäischen Taxa. Bibliotheca Diatomologica, Stuttgart, 26.). In our samples, it occurred in slightly acid pH (6), low conductivity (24.5 µS cm-1) and oligotrophic conditions, only in winter (temperature 16ºC).

Occurrence in samples: artificial substrates (UPCB 63374).

Pinnularia subcapitata var. subrostrata Krammer

Figure: 4AB

Length: 38.5-46.5 µm; width: 6-6.5 µm; striae: 13 in 10 µm.

Ecology: widespread species; common in waters with medium electrolyte concentrations (Krammer 1992KRAMMER, K. 1992. Pinnularia, eine Monographie der europäischen Taxa. Bibliotheca Diatomologica, Stuttgart, 26.). In our samples, it occurred in circumneutral pH (6.7-6.85), low conductivity (22.5-24.5 µS cm-1) and oligotrophic conditions.

Occurrence in samples: artificial (UPCB 63373) and natural (UPCB 63375; UPCB 63376; UPCB 63377) substrates.

Pinnularia subgibba var. undulata Krammer

Figures: 4AC-4AD

Length: 65.1-68.5 µm; width: 7-7.8 µm; striae: 11-12 in 10 µm.

Ecology: previously registered for waters with neutral pH and high conductivity (Noga et al. 2014NOGA, T., PESZEK, Ł., STANEK-TARKOWSKA, J. & PAJĄCZEK, A. 2014. The Pinnularia genus in south-eastern Poland with consideration of rare and new taxa to Poland. Oceanological and Hydrobiological Studies 43(1): 77-99. http://dx.doi.org/10.2478/s13545-014-0120-4
http://dx.doi.org/10.2478/s13545-014-012...
). In Brazil, it was recorded from planktonic samples in Guaraguaçu River (Tremarin et al. 2010TREMARIN, P.I., MOREIRA-FILHO, H. & LUDWIG, T.A.V. 2010. Pinnulariaceae (Bacillaiophyceae) do rio Guaraguaçu, bacia litorânea paranaense, Brasil. Acta Botanica Brasilica 24(2): 335-353.) and from epiphytic samples in a mesotrophic reservoir of the South region (Marra et al. 2016MARRA, R.C., TREMARIN, P.I., ALGARTE, V.M. & LUDWIG, T.A. 2016. Epiphytic diatoms (Diatomeae) from Piraquara II urban reservoir, Paraná state. Biotaneotropica 16(4): e20160200. http://dx.doi.org/10.1590/1676-0611-BN-2016-0200
http://dx.doi.org/10.1590/1676-0611-BN-2...
). This study expanded its occurrence to circumneutral pH (6.7-6.85), low conductivity (22.5-24.5 µS cm-1) and oligotrophic conditions.

Occurrence in samples: artificial (UPCB 63373) and natural (UPCB 63375; UPCB 63376; UPCB 63377) substrates.

Pinnularia submicrostauron Schroeter

Figure: 4AE

Length: 38.4-43.7 µm; width: 5-6.6 µm; striae: 12-13 in 10 µm.

Ecology: previously registered as epiphytic in non-polluted environments, with acid pH (3.95-5.89) and medium to high conductivity (46-94 µS cm-1) (Krammer 1992KRAMMER, K. 1992. Pinnularia, eine Monographie der europäischen Taxa. Bibliotheca Diatomologica, Stuttgart, 26., Veselá 2009VESELÁ, J. 2009. Spatial heterogeneity and ecology of algal communities in an ephemeral sandstone stream in the Bohemian Switzerland National Park, Czech Republic. Nova Hedwigia 88(4-3): 531-547. http://dx.doi.org/10.1127/0029-5035/2009/0088-0531
http://dx.doi.org/10.1127/0029-5035/2009...
, Szulc et al. 2014SZULC, K., BESENYEI, L., SZULC, B. & RAKOWSKA, B. 2014. Diatomological aspects of the Fenn's and Whixall mosses complex (Shropshire, UK). Oceanological and Hydrobiological Studies 43(3): 274-282. http://dx.doi.org/10.2478/s13545-014-0142-y
http://dx.doi.org/10.2478/s13545-014-014...
). In our samples, it occurred in circumneutral pH (6.7), low conductivity (22.5-24.5 µS cm-1) and oligotrophic conditions.

Occurrence in samples: artificial (UPCB 63373) and natural (UPCB 63376; UPCB 63377) substrates.

Pinnularia viridiformis var. viridiformis Krammer

Figure: 4X

Length: 131 µm; width: 17.3 µm; striae: 10 in 10 µm.

Ecology: this species is frequently sampled especially in oligotrophic and mesotrophic environments, with low to moderate conductivity (Krammer 2000KRAMMER, K. 2000. The genus Pinnularia. In Diatoms of Europe 1 (H. Lange-Bertalot) p. 1-703., Bertolli et al. 2010BERTOLLI, L.M., TREMARIN, P.I. & LUDWIG, T.A.V. 2010. Diatomáceas perifíticas em Polygonum hydropiperoides Michaux, reservatório do Passaúna, Região Metropolitana de Curitiba, Paraná, Brasil. Acta Bot. Bras. 24(4):1065-1081. http://dx.doi.org/10.1590/S0102-33062010000400022
http://dx.doi.org/10.1590/S0102-33062010...
), being more abundant in acid pH (Van de Vijver & Beyen 1997VAN DE VIJVER, B. & BEYES, L. 1997. The epiphytic diatom flora of mosses from Strømness Bay area, South Georgia. Polar Biol 17: 492-501. http://dx.doi.org/10.1007/s003000050148
http://dx.doi.org/10.1007/s003000050148...
, Veselá 2014VESELÁ, J. 2009. Spatial heterogeneity and ecology of algal communities in an ephemeral sandstone stream in the Bohemian Switzerland National Park, Czech Republic. Nova Hedwigia 88(4-3): 531-547. http://dx.doi.org/10.1127/0029-5035/2009/0088-0531
http://dx.doi.org/10.1127/0029-5035/2009...
). In our study, it was only recorded from samples of periphyton associated with aquatic macrophytes (75%), in slightly acid to circumneutral pH (6-6.85), low conductivity (24-24.5 µS cm-1) and oligotrophic conditions.

Occurrence in samples: natural substrates (UPCB 63375; UPCB 63376; UPCB 63378).

Pinnularia viridiformis var. minor Krammer.

Figure: 4Y

Length: 52-82.5 µm; width: 11-12.5 µm; striae: 10-12 in 10 µm.

Pinnularia viridiformis var. minor differs from Pinnularia viridis (Nitzsch) Ehrenberg by the valve outline and by the presence of a semi complex raphe (Krammer 2000KRAMMER, K. 2000. The genus Pinnularia. In Diatoms of Europe 1 (H. Lange-Bertalot) p. 1-703.).

Ecology: considered as cosmopolitan (Krammer 2000KRAMMER, K. 2000. The genus Pinnularia. In Diatoms of Europe 1 (H. Lange-Bertalot) p. 1-703.); it is rare in waters with neutral to alkaline pH and in moderate to high conductivity (Cremer et al. 2004CREMER, H., GORE, D., HULTZSCH, N., MELLES, M. & WAGNER, B. 2004. The diatom flora and limnology of lakes in the Amery Oasis, East Antarctica. Polar Biol 27: 513-531. http://dx.doi.org/10.1007/s00300-004-0624-2
http://dx.doi.org/10.1007/s00300-004-062...
, Noga et al. 2014NOGA, T., PESZEK, Ł., STANEK-TARKOWSKA, J. & PAJĄCZEK, A. 2014. The Pinnularia genus in south-eastern Poland with consideration of rare and new taxa to Poland. Oceanological and Hydrobiological Studies 43(1): 77-99. http://dx.doi.org/10.2478/s13545-014-0120-4
http://dx.doi.org/10.2478/s13545-014-012...
). It was previously registered for streams with acid pH and low conductivity, in Central Brazil (França et al. 2017FRANÇA, A.A., DUNCK, B., RODRIGUES, L., FONSECA, B.M. & FELISBERTO, S.A. 2017. Periphytic diatoms (Bacillariophyta) in streams from three Conservation Units of centra Brazil: Pinnularia Ehrenberg. Hoehnea 44(4): 524-538. http://dx.doi.org/10.1590/2236-8906-107/2016
http://dx.doi.org/10.1590/2236-8906-107/...
). In our study, it was recorded from samples of periphyton associated with aquatic macrophytes, in temperatures of 16ºC, acid pH (6), low conductivity (24.5 µS cm-1), and oligotrophic conditions.

This is the first record for Paraná state.

Occurrence in samples: natural substrates (UPCB 63378).

Order NAVICULALES

Family incertae sedis

Chamaepinnularia brasilianopsis Metzeltin & Lange-Bertalot

Figures: 4AJ-4AK

Length: 13.5-13.9 µm; width: 3.5-4.1 µm; striae: 24 in 10 µm.

Ecology: previously described for the Neotropical region (Metzeltin & Lange-Bertalot 1998METZELTIN, D. & LANGE-BERTALOT, H. 1998. Tropical diatoms of South America I. About 700 predominantly rarely known or new taxa representative of the neotropical flora. In Iconogr. Diatomol. (H. Lange-Bertalot , ed.) 5: 1-695.), in mesotrophic waters (Marra et al. 2016MARRA, R.C., TREMARIN, P.I., ALGARTE, V.M. & LUDWIG, T.A. 2016. Epiphytic diatoms (Diatomeae) from Piraquara II urban reservoir, Paraná state. Biotaneotropica 16(4): e20160200. http://dx.doi.org/10.1590/1676-0611-BN-2016-0200
http://dx.doi.org/10.1590/1676-0611-BN-2...
). with circumneutral to slightly alkaline pH, and conductivity between 24.3 and 145 µS cm-1 (Sala et al. 2015SALA, S.E., PLATA-DÍAZ, Y., PEDRAZA, E. & PIMIENTA, A. 2015. Taxonomía y distribucíon de diatomeas epilíticas registradas por primera vez en Colombia. Caldasia 37(1): 125-141. http://dx.doi.org/10.15446/caldasia.v37n1.50814
http://dx.doi.org/10.15446/caldasia.v37n...
). In our study, it was only registered in autumn, from samples of macrophytes, in temperatures of 18.6ºC, circumneutral pH (6.7), low conductivity (22.5 µS cm-1) and oligotrophic conditions.

Occurrence in samples: natural substrates (UPCB 63377).

Chamaepinnularia mediocris (Krasske) Lange-Bertalot & Krammer

Figures: 4AL-4AP

Length: 10-14.7 µm; width: 2.5-3 µm; striae: 21-24in 10 µm.

Ecology: considered as characteristic of oligotrophic environments (van Dam et al. 1994, Hofmann 1994HOFMANN, G. 1994. Aufwuchs-Diatomeen in Seen und ihre Eignung als Indikatoren der Trophie. Biblioth. Diatomol. J. Cramer, Berlin - Stuttgart, 30.), but also cited for mesotrophic and eutrophic waters (Silva et al. 2010SILVA, A.M., TREMARIN, P.I., LUDWIG, T.A.V. & VERCELLINO, I.S. 2010. Diatomáceas perifíticas em um sistema eutrófico brasileiro (Reservatório do Iraí, estado do Paraná). Acta Botanica Brasilica . 24(4): 997-1016. http://dx.doi.org/10.1590/S0102-33062010000400015
http://dx.doi.org/10.1590/S0102-33062010...
, Marra et al. 2016MARRA, R.C., TREMARIN, P.I., ALGARTE, V.M. & LUDWIG, T.A. 2016. Epiphytic diatoms (Diatomeae) from Piraquara II urban reservoir, Paraná state. Biotaneotropica 16(4): e20160200. http://dx.doi.org/10.1590/1676-0611-BN-2016-0200
http://dx.doi.org/10.1590/1676-0611-BN-2...
). It is a good indicator of environments rich in minerals, with moderate to high conductivity, and acid pH (Fránková et al. 2009FRÁNKOVÁ, M., BOJKOVÁ, J., POULÍČKOVÁ, A. & HAJÉK, M. 2009. The structure and species richness of the diatom assemblages of the Western Carpathian pring fens long the gradient of mineral richness. Fottea 9(2): 355-368. http://dx.doi.org/10.5507/fot.2009.035
http://dx.doi.org/10.5507/fot.2009.035...
), and also associated with the process of deglaciation (Fell et al. 2018FELL, S.C., CARRIVICK, J.L., KELLY, M.G., FÜREDER, L. & BROWN, L.E. 2018. Declining glacier cover threatens the biodiversity of alpine river diatom assemblages. Global Change Biology 24: 5828-5840. http://dx.doi.org/ 10.1111/gcb.14454
http://dx.doi.org/ 10.1111/gcb.14454...
). In our study, it occurred in summer (temperature of 27ºC and high acummulated rainfall), in waters with slightly acid to circumneutral pH (6-6.75), low conductivity (22.5-24.5 µS cm-1), and oligotrophic conditions.

Occurrence in samples: artificial (UPCB 63372) and natural (UPCB 63377; UPCB 63378) substrates.

Kobayasiella sp.

Figure: 4O

Length: 39.8 µm; width: 7.4 µm; striae: 15 in 10 µm.

Kobayasiella sp. presents linear-elliptic valves with subcapitate ends. The axial area is linear and straight. The central area is elliptic and delimited by irregular striae that are radiate towards the valve center.

The valve outline is similar to Kobayasiella acidophila Vanhoutte, Kobayasiella subtilissima (Cleve) Lange-Bertalot and Kobayasiella tapajoensis Metzeltin & Lange-Bertalot, but these three latter taxa present smaller size (24.7-31.2 µm, 23-27 µm, and 23-34 µm, respectively) and a higher striae density (34-42, 36-40 and 34-38 in 10 µm, respectively). Kobayasiella sp. is also similar to Kobayasiella floridana Metzeltin & Lange-Bertalot and Kobayasiella krasskei (Metzeltin & Lange-Bertalot) Lange-Bertalot, but these species have larger valves (54-83 µm and 44-50 µm, respectively) and higher striae density (28-32 and 27-28 in 10 µm, respectively) (Metzeltin & Lange-Bertalot 2007METZELTIN, D. & LANGE-BERTALOT, H. 2007. Tropical Diatoms of South America II. Special remarks on biogeographic disjunction. In Iconogr.Diatomol (H. Lange-Bertalot , ed.). Gantner Verlag KG, Ruggell, 18:1-877., 1998METZELTIN, D. & LANGE-BERTALOT, H. 1998. Tropical diatoms of South America I. About 700 predominantly rarely known or new taxa representative of the neotropical flora. In Iconogr. Diatomol. (H. Lange-Bertalot , ed.) 5: 1-695., Vanhoutte et al. 2004VANHOUTTE, K., VERLEYEN, E., VYVERMAN, W., CHEPURNOV, V, & SABBE, K. 2004. The freshwater diatom genus Kobaysiella (Bacillariophyta) in Tasmania, Australia. Australian Systematic Botany 17:483-496. http://dx.doi.org/10.1071/SB03035
http://dx.doi.org/10.1071/SB03035...
).

Occurrence in samples: natural substrates (UPCB 63377).

Family NAVICULACEAE

Navicula cryptocephala Kützing

Figure: 4AF

Length: 23.2-39.2 µm; width: 4.8-6 µm; striae: 12-18 in 10 µm.

Ecology: cosmopolitan; registered for oligotrophic to eutrophic environments, but more abundant in mesotrophic waters (Bertolli et al. 2010BERTOLLI, L.M., TREMARIN, P.I. & LUDWIG, T.A.V. 2010. Diatomáceas perifíticas em Polygonum hydropiperoides Michaux, reservatório do Passaúna, Região Metropolitana de Curitiba, Paraná, Brasil. Acta Bot. Bras. 24(4):1065-1081. http://dx.doi.org/10.1590/S0102-33062010000400022
http://dx.doi.org/10.1590/S0102-33062010...
, Bartozek et al. 2018BARTOZEK, E.C.R., ZORZAL-ALMEIDA, S. & BICUDO, D.C. 2018. Surface sediment and phytoplankton diatoms across a trophic gradient in tropical reservoirs: new records for Brazil and São Paulo State. Hoehnea 45(1): 69-92. http://dx.doi.org/10.1590/2236-8906-51/2017
http://dx.doi.org/10.1590/2236-8906-51/2...
). In our study, it occurred in slightly acid to circumneutral pH (6-6.85), low conductivity (22.5-24.5 µS cm-1), and oligotrophic conditions.

Occurrence in samples: artificial (UPCB 63371; UPCB 63372; UPCB 63373) and natural (UPCB 63375; UPCB 63376; UPCB 63378) substrates.

Navicula cryptotenella Lange-Bertalot.

Figure: 4AG

Length: 20-35 µm; width: 4.5-5.6 µm; striae: 12-18 in 10 µm.

Ecology: widely distributed in oligotrophic to eutrophic conditions (Bertolii et al. 2010BERTOLLI, L.M., TREMARIN, P.I. & LUDWIG, T.A.V. 2010. Diatomáceas perifíticas em Polygonum hydropiperoides Michaux, reservatório do Passaúna, Região Metropolitana de Curitiba, Paraná, Brasil. Acta Bot. Bras. 24(4):1065-1081. http://dx.doi.org/10.1590/S0102-33062010000400022
http://dx.doi.org/10.1590/S0102-33062010...
, Silva et al. 2010SILVA, A.M., TREMARIN, P.I., LUDWIG, T.A.V. & VERCELLINO, I.S. 2010. Diatomáceas perifíticas em um sistema eutrófico brasileiro (Reservatório do Iraí, estado do Paraná). Acta Botanica Brasilica . 24(4): 997-1016. http://dx.doi.org/10.1590/S0102-33062010000400015
http://dx.doi.org/10.1590/S0102-33062010...
, Marra et al. 2016MARRA, R.C., TREMARIN, P.I., ALGARTE, V.M. & LUDWIG, T.A. 2016. Epiphytic diatoms (Diatomeae) from Piraquara II urban reservoir, Paraná state. Biotaneotropica 16(4): e20160200. http://dx.doi.org/10.1590/1676-0611-BN-2016-0200
http://dx.doi.org/10.1590/1676-0611-BN-2...
, Bartozek et al. 2018BARTOZEK, E.C.R., ZORZAL-ALMEIDA, S. & BICUDO, D.C. 2018. Surface sediment and phytoplankton diatoms across a trophic gradient in tropical reservoirs: new records for Brazil and São Paulo State. Hoehnea 45(1): 69-92. http://dx.doi.org/10.1590/2236-8906-51/2017
http://dx.doi.org/10.1590/2236-8906-51/2...
, Santos & Ferragut 2018SANTOS, T.R. & FERRAGUT, C. 2018. Changes in the taxonomic structure of periphytic algae on free-loating crophyte (Utricularia foliosa L.) in relation to macrophyte richness over season. Acta Botanica Brasilica 32(4): 595-601. http://dx.doi.org/10.1590/0102-33062018abb0031
http://dx.doi.org/10.1590/0102-33062018a...
), but most commonly associated with low TP concentrations (Wang et al. 2019WANG, R., XU, M., YANG, H., YANG, X., ZHANG, K., ZHANG, E. & SHEN, J. 2019. Ordered diatom species loss along a total phosphorous gradient in eutrophic lakes of the lower Yangtze River basin, China. Science of the Total Environment 650: 1688-1695. https://doi.org/10.1016/j.scitotenv.2018.09.328
https://doi.org/10.1016/j.scitotenv.2018...
). It occurred in all of our samples, in slightly acid to circumneutral pH (6-6.85), low conductivity (22.5-24.5 µS cm-1), and oligotrophic conditions.

Occurrence in samples: artificial (UPCB 63371; UPCB 63372; UPCB 63373; UPCB 63374) and natural (UPCB 63375; UPCB 63376; UPCB 63377; UPCB 63378) substrates.

Navicula leptostriata Jørgensen

Figure: 4AH

Length: 33-36.3 µm; width: 4.5-4.8 µm; striae: 17-18 in 10 µm.

Ecology: previously registered for environments with moderate to high nutrient concentrations (van Dam et al. 1994, Silva et al. 2010SILVA, A.M., TREMARIN, P.I., LUDWIG, T.A.V. & VERCELLINO, I.S. 2010. Diatomáceas perifíticas em um sistema eutrófico brasileiro (Reservatório do Iraí, estado do Paraná). Acta Botanica Brasilica . 24(4): 997-1016. http://dx.doi.org/10.1590/S0102-33062010000400015
http://dx.doi.org/10.1590/S0102-33062010...
, Ma et al. 2014MA, Y., LI, G., LI, J., ZHOU, H. & JIANG, B. 2014. Seasonal succession of phytoplankton community and its relationship with environmental factors of North Temperate Zone water of the Zhalong wetland, in China. Ecotoxicology 23: 618-625. http://dx.doir.org/10.1007/s10646-014-1231-9
http://dx.doir.org/10.1007/s10646-014-12...
). In our study, it occurred in temperatures < 21ºC, slightly acid and circumneutral pH (6-6.85), low conductivity (22.5-24.5 µS cm-1), and oligotrophic conditions.

Occurrence in samples: artificial (UPCB 63374) and natural (UPCB 63375; UPCB 63377) substrates.

Navicula veneta Kützing

Figure: 4AI

Length: 17 µm; width: 4 µm; striae: 18 in 10 µm.

Ecology: commonly registered for environments rich in nutrients (van Dam et al. 1994VAN DAM, H., MERTENS, A. & SINKELDAM, J. 1994. A coded checklist and ecological indicator values of freshwater diatoms from the Netherlands. Neth. J. Aquatic Ecol. 28(1): 117-133. http://dx.doi.org/10.1007/BF02334251
http://dx.doi.org/10.1007/BF02334251...
, Hofmann 1994HOFMANN, G. 1994. Aufwuchs-Diatomeen in Seen und ihre Eignung als Indikatoren der Trophie. Biblioth. Diatomol. J. Cramer, Berlin - Stuttgart, 30., Silva et al. 2010SILVA, A.M., TREMARIN, P.I., LUDWIG, T.A.V. & VERCELLINO, I.S. 2010. Diatomáceas perifíticas em um sistema eutrófico brasileiro (Reservatório do Iraí, estado do Paraná). Acta Botanica Brasilica . 24(4): 997-1016. http://dx.doi.org/10.1590/S0102-33062010000400015
http://dx.doi.org/10.1590/S0102-33062010...
, Marra et al. 2016MARRA, R.C., TREMARIN, P.I., ALGARTE, V.M. & LUDWIG, T.A. 2016. Epiphytic diatoms (Diatomeae) from Piraquara II urban reservoir, Paraná state. Biotaneotropica 16(4): e20160200. http://dx.doi.org/10.1590/1676-0611-BN-2016-0200
http://dx.doi.org/10.1590/1676-0611-BN-2...
, Casco et al. 2018CASCO, M.A., REYES, I., MARTÍN, G., FERNÁNDEZ, .R., SALA, S.E. & TOJA, J. 2018. Phycological flora of the Guadalquivir river basin. Its value in determining the ecoregionalization of the basin. Limnetica 37(2): 239-248. http://dx.doi.org/10.23818/limn.37.20
http://dx.doi.org/10.23818/limn.37.20...
). In our samples, it only occurred in autumn (temperature of 18.6ºC). This study expanded its occurrence to circumneutral pH (6.7), low conductivity (22.5 µS cm-1) and oligotrophic conditions.

Occurrence in samples: natural substrates (UPCB 63377).

Capartogramma crucicula (Grunow ex Cleve) Ross

Figures: 4P-4Q

Length: 27.5 µm; width: 8.5 µm; striae: 21 in 10 µm.

Ecology: the ecological optimum of this species is difficult to define (Beyene et al. 2014BEYENE, A., AWOKE, A. & TRIEST, L. 2014. Validation of a quantitative method for estimating the indicator power of, diatoms for ecoregional river water quality assessment. Ecological Indicators 37: 58-66. http://dx.doi.org/10.1016/j.ecolind.2013.09.025
http://dx.doi.org/10.1016/j.ecolind.2013...
). It was previously registered for the oligotrophic paleophase (Faustino et al. 2016FAUSTINO, S.B., FONTANA, L., BARTOZEK, E.C.R., BICUDO, C.E.M. & BICUDO, D.C. 2016. Composition and distribution of diatom assemblages from core and surface sediments of a water supply reservoir in Southeastern Brazil. Biota Neotropica: 16(2): e20150129. http://dx.doi.org/10.1590/1676-0611-BN-2015-0129
http://dx.doi.org/10.1590/1676-0611-BN-2...
) and for modern mesotrophic conditions (Marra et al. 2016MARRA, R.C., TREMARIN, P.I., ALGARTE, V.M. & LUDWIG, T.A. 2016. Epiphytic diatoms (Diatomeae) from Piraquara II urban reservoir, Paraná state. Biotaneotropica 16(4): e20160200. http://dx.doi.org/10.1590/1676-0611-BN-2016-0200
http://dx.doi.org/10.1590/1676-0611-BN-2...
). In our study, it occurred in circumneutral pH (6.85), low conductivity (24 µS cm-1) and oligotrophic conditions, only in spring (temperature of 20.8ºC).

Occurrence in samples: artificial substrates (UPCB 63771).

Family STAURONEIDACEAE

Stauroneis neohyalina Lange-Bertalot & Krammer

Figures: 5A-5B

Figure 5
A–B. Stauroneis neohyalina; C. Stauroneis gracilis; D. Stauroneis phoenicenteron; E. Craticula acidoclinata; F. Craticula riparia var. mollenhaurei; G–H. Craticula submolesta; I. Surirella grunowii; J. Iconella curvula; K. Rhopalodia gibberula var. vanheurckii.

Length: 43-52 µm; width: 8-8.7 µm; striae: difficult to distinguish under the LM.

Stauroneis neohyalina differs from Stauroneis gracilior (Rabenhorst) Reichardt by the presence of subcapitate apices, narrower valves and a higher striae density. The striae are difficult to distinguish under the light microscope and the areolae are inconspicuous (Reichardt 1995REICHARDT, E. 1995. Die Diatomeen (Bacillariophyceae) in Ehrenberg's material von Cayenne, Guyana Gallica (1843). In Iconogr. Diatomol. (H. Lange-Bertalot , ed.) 1: 1-107., Lange-Bertalot & Metzeltin 1996LANGE-BERTALOT, H. & METZELTIN, D. 1996. Indicators of oligotrophy-800 taxa representative of three ecologically distinct lake types, Carbonate buffered-Oligodystrophic-Weakly buffered soft water. In Iconogr. Diatomol. (H. Lange-Bertalot, ed.). Gantner Verlag KG, Ruggell, 2:1-390.). In this species, the proximal ends of the raphe are straight and not inflated and teardrop-shaped as in S. gracilior (Cantonati et al. 2017CANTONATI, M., KELLY, M.G. & LANGE-BERTALOT, H. 2017. Freshwater benthic diatoms of Central Europe: over 800 common species used in ecological assessment. English edition with update taxonomy and added species. Schmitten-Oberreifenberg: Koeltz Botanical Books. p. 1-942.).

Widely recorded in different worldwide regions (Guiry & Guiry 2018GUIRY, M.D. 2012. How many species of algae are there? Journal of Phycology 48: 1057-1063. http://dx.doi.org/10.1111/j.1529-8817.2012.01222.x
http://dx.doi.org/10.1111/j.1529-8817.20...
).

This is the first record for Brazil.

Ecology: previously registered for oligotrophic and acidic environments (van Dam et al. 1994VAN DAM, H., MERTENS, A. & SINKELDAM, J. 1994. A coded checklist and ecological indicator values of freshwater diatoms from the Netherlands. Neth. J. Aquatic Ecol. 28(1): 117-133. http://dx.doi.org/10.1007/BF02334251
http://dx.doi.org/10.1007/BF02334251...
, Sienkiewicz 2005SIENKIEWICZ, E. 2005. Comparison of subfossil diatoms (Bacillariophyta) from two oligotrophic lakes: Maly Staw (Karkonosze MTS., Poland) and Somaslampi (Lapland, Finland). Polish Geological Institute Special Papers. 16: 109-115., Van de Vijver et al. 2005VAN DE VIJVER, B., GREMMEN, N.J. & BEYENS, L. 2005. The genus Stauroneis (Bacillariophyceae) in the Antartic region. J. Biogeogr. 32: 1791-1798. http://dx.doi.org/10.1111/j.1365-2699.2005.01325.x
http://dx.doi.org/10.1111/j.1365-2699.20...
, Krstić et al. 2012KRSTIĆ, S.S., ZECH, W., OBREHT, I., SVIRČEV, Z. & MARCOVIĆ, S.B. 2012. Late quaternary environmental changes in Helambu Himal, Central Nepal, recorded in the diatom flora assemblage composition and geochemistry of Lake Panch Pokhari. J. Paleolimnol. 47: 113-124. https://doi.org/10.1007/s10933-011-9563-4
https://doi.org/10.1007/s10933-011-9563-...
). In our samples, it occurred in slightly acid to circumneutral pH (6-6.75), low conductivity (22.5-24.5 µS cm-1) and oligotrophic conditions, in summer (temperature of 27ºC).

Occurrence in samples: artificial (UPCB 63373) and natural (UPCB 63376; UPCB 63378) substrates.

Stauroneis gracilis Ehrenberg

Figure: 5C

Length: 83.5 µm; width: 13.5 µm; striae: 23 in 10 µm.

Ecology: considered as characteristic of oligotrophic environments (Dixit & Smol 1995DIXIT, S.S. & SMOL, J.P. 1995. Diatom evidence of past water quality changes in Adirondack Seepage Lakes (New York, U.S.A.). Diat. Res. 10(1): 113-129. http://dx.doi.org/10.1080/0269249X.1995.9705331
http://dx.doi.org/10.1080/0269249X.1995....
); it is rare in mesotrophic and eutrophic conditions (Silva et al. 2010SILVA, A.M., TREMARIN, P.I., LUDWIG, T.A.V. & VERCELLINO, I.S. 2010. Diatomáceas perifíticas em um sistema eutrófico brasileiro (Reservatório do Iraí, estado do Paraná). Acta Botanica Brasilica . 24(4): 997-1016. http://dx.doi.org/10.1590/S0102-33062010000400015
http://dx.doi.org/10.1590/S0102-33062010...
, Marra et al. 2016MARRA, R.C., TREMARIN, P.I., ALGARTE, V.M. & LUDWIG, T.A. 2016. Epiphytic diatoms (Diatomeae) from Piraquara II urban reservoir, Paraná state. Biotaneotropica 16(4): e20160200. http://dx.doi.org/10.1590/1676-0611-BN-2016-0200
http://dx.doi.org/10.1590/1676-0611-BN-2...
) and has its optimum in conditions of low conductivity (Pestryakova et al. 2018PESTRYAKOVA, L.A., HERZSCHUH, U., GORODNICHEV, R. & WETTERICH, S. 2018. The sensitivity of diatom taxa from Yakutian lakes (north-eastern Siberia) to electoral conductivity nd other environmental variables. Polar Research 37:1485625. https://doi.org/10.1080/17518369.2018.1485625
https://doi.org/10.1080/17518369.2018.14...
). In our study, it only occurred from samples of aquatic macrophytes, in circumneutral pH (6.7), low conductivity (22.5 µS cm-1) and oligotrophic conditions, in autumn (temperature of 18.6ºC).

Occurrence in samples: natural substrates (UPCB 63377).

Stauroneis phoenicenteron (Nitzsch) Ehrenberg

Figure: 5D

Length: 96.5-116.5 µm; width: 18.2-22.5 µm; striae: 18-19 in 10 µm.

Ecology: considered as characteristic of meso-eutrophic environments (van Dam et al. 1994, Silva et al. 2010SILVA, A.M., TREMARIN, P.I., LUDWIG, T.A.V. & VERCELLINO, I.S. 2010. Diatomáceas perifíticas em um sistema eutrófico brasileiro (Reservatório do Iraí, estado do Paraná). Acta Botanica Brasilica . 24(4): 997-1016. http://dx.doi.org/10.1590/S0102-33062010000400015
http://dx.doi.org/10.1590/S0102-33062010...
, Bertolii et al. 2010BERTOLLI, L.M., TREMARIN, P.I. & LUDWIG, T.A.V. 2010. Diatomáceas perifíticas em Polygonum hydropiperoides Michaux, reservatório do Passaúna, Região Metropolitana de Curitiba, Paraná, Brasil. Acta Bot. Bras. 24(4):1065-1081. http://dx.doi.org/10.1590/S0102-33062010000400022
http://dx.doi.org/10.1590/S0102-33062010...
), it has its optimum in conditions of intermediate conductivity (Pestryakova et al. 2018PESTRYAKOVA, L.A., HERZSCHUH, U., GORODNICHEV, R. & WETTERICH, S. 2018. The sensitivity of diatom taxa from Yakutian lakes (north-eastern Siberia) to electoral conductivity nd other environmental variables. Polar Research 37:1485625. https://doi.org/10.1080/17518369.2018.1485625
https://doi.org/10.1080/17518369.2018.14...
) and acid to circumneutral pH (Ma et al. 2014MA, Y., LI, G., LI, J., ZHOU, H. & JIANG, B. 2014. Seasonal succession of phytoplankton community and its relationship with environmental factors of North Temperate Zone water of the Zhalong wetland, in China. Ecotoxicology 23: 618-625. http://dx.doir.org/10.1007/s10646-014-1231-9
http://dx.doir.org/10.1007/s10646-014-12...
). In this samples, it occurred in slightly to circumneutral pH (6-6.7), low conductivity (22.5-24.5 µS cm-1) and oligotrophic conditions, in autumn (temperature < 21ºC).

Occurrence in samples: artificial (UPCB 63373; UPCB 63374) and natural (UPCB 63377) substrates.

Craticula acidoclinata Lange-Bertalot & Metzeltin

Figure: 5E

Length: 65-1-74.2 µm; width: 17.9-18.5 µm; striae: 15 in 10 µm; areolae: 24 in 10 µm.

Craticula acidoclinata differs from Craticula ambigua (Ehrenberg) Mann by the presence of subrostrate apices and broadly rounded ends in the valves (distinctly protracted and rostrate in C. ambigua). Craticula cuspidata (Kützing) Mann has wider valves with narrower apices (Lange-Bertalot & Metzeltin 1996LANGE-BERTALOT, H. & METZELTIN, D. 1996. Indicators of oligotrophy-800 taxa representative of three ecologically distinct lake types, Carbonate buffered-Oligodystrophic-Weakly buffered soft water. In Iconogr. Diatomol. (H. Lange-Bertalot, ed.). Gantner Verlag KG, Ruggell, 2:1-390.).

Ecology: registered for acid environments, poor in nutrients (Cantonati et al. 2017CANTONATI, M., KELLY, M.G. & LANGE-BERTALOT, H. 2017. Freshwater benthic diatoms of Central Europe: over 800 common species used in ecological assessment. English edition with update taxonomy and added species. Schmitten-Oberreifenberg: Koeltz Botanical Books. p. 1-942.). It was previously found in Rio Tapajós, Brazil (Metzeltin & Lange-Bertalot 1998METZELTIN, D. & LANGE-BERTALOT, H. 1998. Tropical diatoms of South America I. About 700 predominantly rarely known or new taxa representative of the neotropical flora. In Iconogr. Diatomol. (H. Lange-Bertalot , ed.) 5: 1-695.). In our samples, it occurred in circumneutral pH (6.7), low conductivity (22.5 µS cm-1) and oligotrophic conditions, in autumn (temperature < 21ºC).

This is the first record for Paraná state.

Occurrence in samples: natural substrates (UPCB 63377).

Craticula riparia var. mollenhaurei Lange-Bertalot.

Figure: 5F

Length: 33.5 µm; width: 7 µm; striae: 24 in 10 µm.

Craticula riparia var. mollenhaurei resembles Craticula riparia (Hustedt) Lange-Bertalot var. riparia Lange-Bertalot in the valve outline but differs from the latter by the presence of longer and wider valves (35-50 µm and 8-10.5 µm) and a lower striae density (15-18 in 10 µm). Craticula riparia var. riparia is common in eutrophic environments with high conductivity (Lange-Bertalot 2001LANGE-BERTALOT, H. 2001. Navicula sensu stricto. 10 Genera separated from Navicula sensu lato. Frustulia. Diatoms of Europe: diatoms of the European inland waters and comparable habitats. Ruggell: A.R.G. Gantner Verlag. K.G. 2:1-526., van Dam et al. 1994VAN DAM, H., MERTENS, A. & SINKELDAM, J. 1994. A coded checklist and ecological indicator values of freshwater diatoms from the Netherlands. Neth. J. Aquatic Ecol. 28(1): 117-133. http://dx.doi.org/10.1007/BF02334251
http://dx.doi.org/10.1007/BF02334251...
).

Ecology: previously registered for slightly acid to neutral waters, with low conductivity (Lange-Bertalot 2001LANGE-BERTALOT, H. 2001. Navicula sensu stricto. 10 Genera separated from Navicula sensu lato. Frustulia. Diatoms of Europe: diatoms of the European inland waters and comparable habitats. Ruggell: A.R.G. Gantner Verlag. K.G. 2:1-526., Lange-Bertalot 1993LANGE-BERTALOT, H. 1993. 85 Neue Taxa und über 100 weitere neu definierte Taxa ergänzend zur Süsswasserflora von Mitteleuropa. Bibliotheca Diatomologica 27: 1-164.). In our samples, it occurred in circumneutral pH (6.7), low conductivity (22.5 µS cm-1) and oligotrophic conditions, in.autumn (temperature < 21ºC).

This is the first record for Brazil.

Occurrence in samples: natural substrates (UPCB 63377).

Craticula submolesta (Hustedt) Lange-Bertalot

Figures: 5G-5H

Length: 16.8-17.1 µm; width: 4-4.3 µm; striae: 22-24 in 10 µm.

Ecology: considered as characteristic of oligotrophic environments (Lange-Bertalot & Metzeltin 1996LANGE-BERTALOT, H. & METZELTIN, D. 1996. Indicators of oligotrophy-800 taxa representative of three ecologically distinct lake types, Carbonate buffered-Oligodystrophic-Weakly buffered soft water. In Iconogr. Diatomol. (H. Lange-Bertalot, ed.). Gantner Verlag KG, Ruggell, 2:1-390.), it is rarely found in mesotrophic conditions (Marra et al. 2016MARRA, R.C., TREMARIN, P.I., ALGARTE, V.M. & LUDWIG, T.A. 2016. Epiphytic diatoms (Diatomeae) from Piraquara II urban reservoir, Paraná state. Biotaneotropica 16(4): e20160200. http://dx.doi.org/10.1590/1676-0611-BN-2016-0200
http://dx.doi.org/10.1590/1676-0611-BN-2...
). In our samples, it occurred in circumneutral pH (6.7), low conductivity (22.5 µS cm-1) and oligotrophic conditions, in autumn (temperature < 21ºC).

Occurrence in samples: natural substrates (UPCB 63377).

Family BACILLARIACEAE

Nitzschia acidoclinata Lange-Bertalot

Figure: 4U-4V

Length: 21-38.7 µm; width: 2.5-3 µm; indistinct striae; fibulae: 13-14 in 10 µm.

Ecology: previously registered for oligo-mesotrophic environments (van Dam et al. 1994, Hofmann 1994HOFMANN, G. 1994. Aufwuchs-Diatomeen in Seen und ihre Eignung als Indikatoren der Trophie. Biblioth. Diatomol. J. Cramer, Berlin - Stuttgart, 30.). In our samples, it occurred in temperatures < 21ºC, slightly acid to circumneutral pH (6-6.85), low conductivity (22.5-24.5 µS cm-1) and oligotrophic conditions.

Occurrence in samples: artificial (UPCB 63373; UPCB 63374) and natural (UPCB 63375; UPCB 63378) substrates.

Nitzschia nana Grunow

Figure: 4W

Length: 58.3, width: 5.2 µm; indistinct striae; fibulae: 10 in 10 µm.

Ecology: it avoids saprobic environments (Cantonati et al. 2017CANTONATI, M., KELLY, M.G. & LANGE-BERTALOT, H. 2017. Freshwater benthic diatoms of Central Europe: over 800 common species used in ecological assessment. English edition with update taxonomy and added species. Schmitten-Oberreifenberg: Koeltz Botanical Books. p. 1-942.). In our samples, it occurred in circumneutral pH (6.85), low conductivity (24 µS cm-1) and oligotrophic conditions, in spring (temperature < 21ºC).

Occurrence in samples: natural substrates (UPCB 63375)

Nitzschia semirobusta Lange-Bertalot.

Figures: 4R-4T

Length: 16-20 µm; width: 4.5 -5 µm; striae: 16-18 in 10 µm; fibulae: 7 in 10 µm.

Nitzschia semirobusta differs from Nitzschia amphibia Grunow by the presence of longer fibulae and from Nitzschia amphibioides Hustedt by having a greater striae density. Denticula kuetzingii Grunow is distinguished from Nitzschia semirobusta by the presence of fibulae that are extended completely and with similar thickness from margin to margin in the first species (Lange-Bertalot 1993), while in the latter species the fibulae decrease in thickness towards the margin.

Ecology: Due to the taxonomic problems and misidentification, the ecological preference of N. semirobusta is unclear. Therefore, information on its occurrence and ecological preferences is of high relevance for delimiting the ecological requirements and tolerances of N. semirobusta. It was frequently registered for oligo- to mesotrophic reservoirs in São Paulo state (Bartozek et al. 2018BARTOZEK, E.C.R., ZORZAL-ALMEIDA, S. & BICUDO, D.C. 2018. Surface sediment and phytoplankton diatoms across a trophic gradient in tropical reservoirs: new records for Brazil and São Paulo State. Hoehnea 45(1): 69-92. http://dx.doi.org/10.1590/2236-8906-51/2017
http://dx.doi.org/10.1590/2236-8906-51/2...
). In our samples, it occurred in slightly acid to circumneutral pH (6-6.85), low conductivity (22.5-24.5 µS cm-1) and oligotrophic conditions.

This is the first record for Paraná state.

Occurrence in samples: artificial (UPCB 63371; UPCB 63374) and natural (UPCB 63375; UPCB 63376; UPCB 63377; UPCB 63378) substrates.

Hantzschia amphioxys (Ehrenberg) Grunow

Figure: 4L-4M

Length: 23.5-45 µm; width: 5-5.6 µm; indistinct striae; fibulae: 8-9 in 10 µm.

Ecology: common in soil and aerial habitats (Jahn et al. 2014JAHN, R., KUSBER, W-H. & LANGE-BERTALOT, H. 2014. Typification and taxonomy of Hantzschia amphioxys (Ehrenberg) Grunow (Bacillariophyta): type of the genus name Hantzschia Grunow. Nova Hedwigia 143: 103-110. http://dx.doi.org/ 10.1127/1438-9134/2014/005
http://dx.doi.org/ 10.1127/1438-9134/201...
), and considered as tipically indifferent to trophic conditions (van Dam et al. 1994VAN DAM, H., MERTENS, A. & SINKELDAM, J. 1994. A coded checklist and ecological indicator values of freshwater diatoms from the Netherlands. Neth. J. Aquatic Ecol. 28(1): 117-133. http://dx.doi.org/10.1007/BF02334251
http://dx.doi.org/10.1007/BF02334251...
, Hofmann 1994HOFMANN, G. 1994. Aufwuchs-Diatomeen in Seen und ihre Eignung als Indikatoren der Trophie. Biblioth. Diatomol. J. Cramer, Berlin - Stuttgart, 30.). It is rarely found in waters poor in nutrients, being more common in mesotrophic environments (Bertolli et al. 2010BERTOLLI, L.M., TREMARIN, P.I. & LUDWIG, T.A.V. 2010. Diatomáceas perifíticas em Polygonum hydropiperoides Michaux, reservatório do Passaúna, Região Metropolitana de Curitiba, Paraná, Brasil. Acta Bot. Bras. 24(4):1065-1081. http://dx.doi.org/10.1590/S0102-33062010000400022
http://dx.doi.org/10.1590/S0102-33062010...
, Bartozek et al. 2018BARTOZEK, E.C.R., ZORZAL-ALMEIDA, S. & BICUDO, D.C. 2018. Surface sediment and phytoplankton diatoms across a trophic gradient in tropical reservoirs: new records for Brazil and São Paulo State. Hoehnea 45(1): 69-92. http://dx.doi.org/10.1590/2236-8906-51/2017
http://dx.doi.org/10.1590/2236-8906-51/2...
, Cuña-Rodríguez et al. 2018CUNÃ-RODRÍGUEZ, C., PIOVANO, E., DEL PUERTO, L., INDA, H. & GARCÍA-RODRÍGUEZ, F. 2018. On the relationship between holocene environmental variability and the diatomcomposition in the Peña Laggon, Se Uruguay. Ameghiniana 55(4): 423-436.) and eutrophic conditions (Silva et al. 2010SILVA, A.M., TREMARIN, P.I., LUDWIG, T.A.V. & VERCELLINO, I.S. 2010. Diatomáceas perifíticas em um sistema eutrófico brasileiro (Reservatório do Iraí, estado do Paraná). Acta Botanica Brasilica . 24(4): 997-1016. http://dx.doi.org/10.1590/S0102-33062010000400015
http://dx.doi.org/10.1590/S0102-33062010...
). Previous studies associated this species with cold waters (Darling et al. 2017DARLING, J.P., GARLAND, D.D., STANISH, L.F., ESPOSITO, R.M.M., SOKOL, E.R. & MCKNIGHT, D.M. 2017. Thermal autecology describes the occurrence patterns of four benthic diatoms in McMurdo Dry Valley streams. Polar Biol 40: 2381-2396. https://doi.org/10.1007/s00300-017-2151-y
https://doi.org/10.1007/s00300-017-2151-...
), however, in our samples it only occurred in summer (temperature 27ºC), in circumneutral pH (6.75), low conductivity (24.5 µS cm-1) and oligotrophic conditions.

Occurrence in samples: natural substrates (UPCB 63376).

Family RHOPALODIACEAE

Rhopalodia gibberula var. vanheurckii O. Müller

Figure: 5K

Length: 35.1-36.3 µm; width: 8-8.5 µm; striae: 14-19 in 10 µm; transapical ribs: 4-5 in 10 µm.

Ecology: considered as an alkalinophilous species (van Dam et al. 1994VAN DAM, H., MERTENS, A. & SINKELDAM, J. 1994. A coded checklist and ecological indicator values of freshwater diatoms from the Netherlands. Neth. J. Aquatic Ecol. 28(1): 117-133. http://dx.doi.org/10.1007/BF02334251
http://dx.doi.org/10.1007/BF02334251...
). In our samples, it occurred in slightly acid pH (6), low conductivity (24.5 µS cm-1) and oligotrophic conditions, only in winter (temperature 16ºC),

Occurrence in samples: natural substrates (UPCB 63378).

Family SURIRELLACEAE

Surirella grunowii Kulikovskiy, Lange-Bertalot & Witkovski.

Figure: 5I

Length: 62.4-76.1 µm; width: 11.5-11.6 µm; striae: difficult to distinguish; alar canals: 3-4 in 10 µm.

Surirella linearis var. constricta Grunow was synonymized with S. grunowii by Kulikovskiy et al. (2010)KULIKOVSKIY, M.S., LANGE-BERTALOT, H. , WITKOWSKI, A., DOROFEYUK, N.I. & GENKAL, S.I. 2010. Diatom assemblages from Sphagnum bogs of the world. I. Nur bog in northern Mongolia. Biblio. Diatomol. 55: 1-326..

Ecology: previously registered for oligo-mesotrophic environments (van Dam et al. 1994). In our samples, it occurred in circumneutral pH (6.7-6.85), low conductivity (22.5-24 µS cm-1) and oligotrophic conditions, in spring and autumn seasons (temperature < 21ºC).

Occurrence in samples: artificial (UPCB 63371) and natural (UPCB 63377) substrates.

Iconella curvula (Smith) Ruck & Nakov

Figure: 5J

Length: 92 µm; width: 4 µm; indistinct striae; alar canals: 7 in 10 µm.

Ecology: cited as Stenopterobia curvula (Smith) Krammer, it was registered for oligotrophic (van Dam et al. 1994VAN DAM, H., MERTENS, A. & SINKELDAM, J. 1994. A coded checklist and ecological indicator values of freshwater diatoms from the Netherlands. Neth. J. Aquatic Ecol. 28(1): 117-133. http://dx.doi.org/10.1007/BF02334251
http://dx.doi.org/10.1007/BF02334251...
) and mesotrophic environments (Marra et al. 2016MARRA, R.C., TREMARIN, P.I., ALGARTE, V.M. & LUDWIG, T.A. 2016. Epiphytic diatoms (Diatomeae) from Piraquara II urban reservoir, Paraná state. Biotaneotropica 16(4): e20160200. http://dx.doi.org/10.1590/1676-0611-BN-2016-0200
http://dx.doi.org/10.1590/1676-0611-BN-2...
). In our samples, it occurred in circumneutral pH (6.75), low conductivity (24.5 µS cm-1) and oligotrophic conditions, only in summer (temperature 27ºC).

Occurrence in samples: natural substrates (UPCB 63376).

Conclusions

The inventory performed at the Piraquara I reservoir brings an important contribution to the diatom diversity from oligotrophic environments. We registered the first occurrence of five diatom species in Brazil and seven in the state of Paraná, contributing to the geographic distribution and the ecology of the identified species. Finally, fourteen periphytic species extended their ecological limits of pH, conductivity and trophic preferences.

Acknowledgments

To "Conselho Nacional de Desenvolvimento Científico e Tecnológico" (CNPq) for the master´s scholarship (AMSL), scientific productivity scholarship (TAVL) and financial support for the project (CTHidro-555397/2006-8). To IAP and SANEPAR for providing chemical data and field sampling support and to Laboratório de Ficologia UFPR for facilitating the use of the optical microscope.

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Publication Dates

  • Publication in this collection
    28 Mar 2019
  • Date of issue
    2019

History

  • Received
    25 Apr 2018
  • Reviewed
    16 Dec 2018
  • Accepted
    21 Feb 2019
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