Monoraphidium and Ankistrodesmus ( Chlorophyceae , Chlorophyta ) from Pantanal dos Marimbus , Chapada Diamantina , Bahia State , Brazil

(Monoraphidium and Ankistrodesmus (Chlorophyceae, Chlorophyta) from Pantanal dos Marimbus, Chapada Diamantina, Bahia State, Brazil).This study aimed to identify taxa belonging to the genera Monoraphidium and Ankistrodesmus (Chlorophyceae, Chlorophyta) in two wetland areas of Pantanal dos Marimbus (Baiano and Remanso) in the Marimbus-Iraquara Environmental Protection Area, Bahia State, Brazil, and contribute to the knowledge of Chlorophyceae of Bahia State and Brazil. The materials studied, which were of periphytic and metaphytic origin, came from 64 samples collected in April and June 2011. We identified 18 taxa, 13 from Monoraphidium and five from Ankistrodesmus. Eight taxa were additions to the continental microalgae flora of Northeastern Brazil. Two taxa rarely found in Brazil were collected during the study: Monoraphidium dybowskii and M. litorale.


Introduction
The Pantanal dos Marimbus is considered one of the main ecosystems in Chapada Diamantina and corresponds to an extensive wetland area that is subject to periodic flooding, draining most of the region's rivers (Sema 2011).The Bahia State Government transformed this region into a protected area (Marimbus-Iraquara EPA) due to its rich biological diversity with Decree nº 2216 of June 14, 1993.
According to Taniguchi et al. (2005), despite the immense representation of wetlands in Brazil, knowledge regarding the algal communities in these aquatic systems is still scarce.Most phycological studies in these environments highlight the Chlorophyceae class as being the most common group (De-Lamonica-Freire & Heckman 1996, De-Lamonica-Freire & Sant'Anna 1993).This group generally stands out due to its extensive distribution, diversity, and species richness, in addition to being essential in ecological studies (Comas 1996).
The two genera Monoraphidium Komárková-Legnerová and Ankistrodesmus Corda are among those that deserve attention in the Chlorophyceae class.
Both genera are commonly found in many continental tropical and temperate aquatic environments, primarily those with high nutrient content (Reynolds 1984).In addition, representatives of these genera are widely used in physiological studies due to their rapid growth rate in culture (Sipaúba-Tavares et al. 1999, El-Sheekh et al. 2003).
The knowledge of the Monoraphidium and Ankistrodesmus genera in Bahia State is scarce and currently restricted to studies by Menezes et al. (2012) and reports of ecological content by Fuentes et al. (2010) and Santana (2011), in which the species are represented only by listings.Taxonomic studies with descriptions and illustrations of these genera do not exist for Bahia State.
This study aimed to conduct a taxonomic inventory of the Monoraphidium and Ankistrodesmus genera at two areas in the Pantanal dos Marimbus (Remanso and Baiano), Chapada Diamantina, to contribute to the knowledge of Chlorophyceae of Bahia State and Brazil.

Material and methods
The Pantanal dos Marimbus corresponds to a flood plain formed by the confluence of the Santo Antônio, Utinga, and São José Rivers, covering the municipalities of Lençóis and Andaraí in Chapada Diamantina, Bahia State, Brazil.The Marimbus are subdivided in four areas (Remanso, Fazenda Velha, Ferreira and Baiano).
The study was conducted in two areas of the Pantanal dos Marimbus (Remanso and Baiano) (figure 1).The Marimbus do Remanso (41º20'W, 12º40'S), is located at the municipality of Lençóis and near the village of Remanso, and is characterized by calm waters (most zones) with pH 6.6-7.6 and average transparency (2.1 m).It is notable the influence of the Santo Antonio River in the dynamics of the environment, especially in the narrower parts, in which current flow is higher.
The Marimbus do Baiano (41º18'W, 12º45'S), located in the municipality of Andaraí, consists of several interconnected lakes such as Lagoa do Baiano, Lagoa da Isca, Lagoa dos Paus and Olho D'Agua do Peri.These subdivisions are most used by local fishermen in the dry season, when the water regime of the Santo Antonio River is well below normal, and then there is no interconnection between them.Considering this subdivision, the samples of the present study, collected in Marimbus do Baiano, were concentrated in the Lagoa do Baiano.The area is characterized also by calm waters with pH 6.0-7.2 and average transparency (0.9 m).The Marimbus areas have several macrophytes such as Utricularia foliosa L., Cabomba haynesii Wiersema, Eichhornia azurea (Sw.)Kunth., Nymphaea ampla (Salisb.)DC, Salvinia auriculata Aubl.and Hydrocleys nymphoides (Humb. & Bonpl. ex Willd.).
Sixty four samples of periphytic and metaphytic material studied were collected during April and June 2011 (beginning of the dry season) and came mainly from these macrophytes cited.All collections were made using standardized techniques for taxonomic studies of continental microalgae (Bicudo & Menezes 2006).
The metric limits of the specimens were obtained using an ocular micrometer, and the photomicrographs were acquired with a digital camera coupled to an optical microscope.The species were identified based on the specialized literature; the classification system adopted follows Komárek & Fott (1983).
Samples were preserved in Transeau solution follow Bicudo & Menezes (2006), and incorporated in the liquid collection at the Herbarium of the Universidade Estadual de Feira de Santana (HUEFS).

Results and discussion
In the present study on Pantanal do Marimbus, 18 taxa, 13 from Monoraphidium Corda and five from Ankistrodesmus Komárková-Legnerová were identified:
Cells in colonies, rarely solitary, forming clumps or loose to dense fascicles, parallel or sometimes spirally arranged around each other.Fusiform cells, longer than wide, may be straight, curved, or sigmoid, with gradually or abruptly tapered ends; smooth cell wall; parietal chloroplast without pyrenoids.Reproduction by 2-16 autospores, arranged in parallel within the mother cell, which are released after the breakup of the cell wall (Comas 1996).
According to Komárek (1983), Ankistrodesmus bernardii usually forms colonies with many cells that are variable in length.This species is closely related to A. densus, which differs by having curved or sigmoid cells throughout its length, in addition to having longer cells.
According to Komárek (1983) and Comas (1996), A. bernardii is a tropical species that occurs in periphytic communities from meso-eutrophic aquatic environments.
The populations analyzed in the study area are in accordance to the descriptions and illustrations reported by Komárek & Fott (1983), Comas (1996), and Nogueira & Oliveira (2009).
This report constitutes the first citation of the species for Northeastern Brazil.Geographic distribution in Brazil: Amazonas, Tocantins, Goiás, Minas Gerais, São Paulo, Rio de Janeiro, Paraná (Menezes et al. 2012) and Bahia (present study).

Ankistrodesmus densus
The populations studied agreed with the descriptions and illustrations reported by Komárek & Fott (1983) and Sant'Anna (1984); however, the analyzed cells are longer than those reported by Bortolini et al. (2010).
The taxon is likely cosmopolitan and is found in neutral or acidic waters (Comas 1996, John & Tsarenko 2002).

Ankistrodesmus falcatus
According to Hindák (1984), when there is displacement of the two central cells of Ankistrodesmus falcatus forming angles close or equal to 90º, the colony has similar morphology to that of A. fusiformis; however, this species is distinguished by its smaller cell sizes.
The Ankistrodesmus falcatus populations examined in this study are consistent with the descriptions and illustrations reported by Komárek & Fott (1983), Nogueira (1991), andComas (1996), although the maximum metric limits recorded for specimens from Bahia State have been slightly higher than those found by these authors.calm and oligotrophic waters, and to occur in both planktonic and periphytic environments.

Ankistrodesmus fusiformis
In the studied A. fusiformis populations, there were varied numbers of cells, predominantly in small, ephemeral colonies with 2-4 cells, although colonies with eight cells were found.In addition, there is a cell polymorphism, with cell shape being sometimes straight and sometimes slightly curved.
Ankistrodesmus fusiformis was previously cited for Bahia State by Fuentes et al. (2010) and Santana (2011) from analysed material from the Rio de Contas and Almada River, respectively.The authors did not provided comments or illustrations of the material studied.Therefore, we consider the present study to be the first time that the occurrence of the species was confirmed in Bahia State.
Morphologically, Ankistrodesmus spiralis is similar to A. densus; however, this species is distinguished by having a colony with 16 or more cells, less torsion throughout the cell, and larger cell measurements (wider and longer cells).
The populations analyzed in the Pantanal dos Marimbus agreed with the descriptions and illustrations presented by Komárek & Fott (1983), Hindák (1988), andBortolini et al. (2010), although the cell dimensions shown by these latter authors were smaller than those found in the studied specimens.
According to John & Tsarenko (2002), A. spiralis is cosmopolitan and is common in acidic aquatic environments.This report constitutes the first citation of the species for Bahia State.
Single cells, fusiform, cylindrical, longer than broad, straight, curved or sigmoid, sometimes spiral, gradually tapered towards the apex, which may be tapered or rounded; smooth cell wall; parietal chloroplast, without pyrenoids.Reproduction by 4-8 autospores, arranged in series within the mother cell, which are released after breaking up the wall of the mother cell into two parts (Comas 1996).
Monoraphidium arcuatum is morphologically similar to M. indicum Hindák; however, this species differs by having larger cell dimensions and being generally more rounded and curved.

Monoraphidium caribeum
According to Comas (1996), Monoraphidium caribeum differs from M. arcuatum only by cell dimensions.In addition to these dimensions, it is possible to observe in the analyzed populations that cells of M. arcuatum have gradually tapered apices.
The material analyzed in the present study agreed with the descriptions and illustrations of specimens studied by Komárek & Fott (1983), Comas (1996), and Nogueira (1999).
The species is cosmopolitan and is found primarily in the plankton and periphyton from eutrophic aquatic environments (Comas 1996).
This report constitutes the first citation of the species for Northeastern Brazil.Geographic distribution in Brazil: Amazonas, Goiás, São Paulo, Rio de Janeiro, Paraná (Menezes et al. 2012) and Bahia (present study).

Monoraphidium circinale
Morphologically, Monoraphidium circinale is similar to M. minutum; however, this species differs by having cylindrical poles and generally broader cells.
The specimens analyzed in the Pantanal dos Marimbus have slightly smaller cell measurements than those reported by Nogueira (1999) and Hindák (1988); however, they are consistent with the description and illustrations reported by Komárek & Fott (1983).
According to Komárek & Fott (1983), the species is usually found in the plankton, primarily in eutrophic and alkaline environments.
The material studied agreed with the descriptions and illustrations presented by Komárek (1983), Comas (1996), Tucci et al. (2006), andHentschke &Torgan (2010), although the maximum cell measurements reported by the first two authors are larger than those of the specimens studied.
Thus far, the M. contortum recorded for the Bahia State has appeared only on species lists (Fuentes et al. 2010, Santana 2011, Menezes et al. 2012), where the lack of data such as descriptions and illustrations makes it difficult to study these species.Therefore, we consider the present study to be the first confirmed report of the occurrence of these species in Bahia State.

Monoraphidium dybowskii (Woloszýnska
According to Hindák (1977), Monoraphidium dybowskii is distinguished from other species in the genus by having cylindrical cells that are straight with rounded apices.Morphologically, the taxon resembles M. obtusum; however, this species differs by having larger cell dimensions and straighter apices.
Until the 1980s, the species was known only in Central Europe (Komárek & Fott 1983).Comas (1996) reported the taxon occurring in aquatic environments ranging from oligotrophic to Cuban mesotrophic, as a part of the plankton.In Brazil, the species was initially reported in an oligotrophic lake in the municipality of São Paulo (Lopes 1999) and in a meso-eutrophic reservoir in Goiás State (Nogueira 1999).

Monoraphidium griffithii (Berkeley
The presence of fusiform cells that are straight with tapered apices approach Monoraphidium griffithii with M. komarkovae and M. tortile (W.West & G.S. West) Komárková-Legnorová; however, M. komarkovae differs by having a higher length/ width ratio and more tapered and pointed apices, while M. tortile differs by having less cell dimensions.
The specimens analyzed are consistent with the descriptions and illustrations by Komárek (1983), Comas (1996), Ferragut et al. (2005), Tucci et al. (2006), andHentschke &Torgan (2010).Fuentes et al. (2010) and Santana (2011) reported the occurrence of M. griffithii in Bahia State but did not provide descriptions or illustrations to allow for the restudy of these species.Therefore, we consider the present study to be the first confirmed report of the occurrence of this species in Bahia State.
According to Comas (1996), M. griffithii is likely a cosmopolitan species that is usually found in the plankton from mesotrophic and eutrophic environments.
The first reference to M. irregulare for Bahia State appears in Menezes et al. (2012), but the author did not provide a description or illustration of the material to allow for the restudy of the species.Therefore, we consider the present study to be the first confirmed report of the occurrence of this species in Bahia State.

Monoraphidium komarkovae
The populations from Bahia State analyzed during this study agreed with the descriptions and illustrations reported by Komárek & Fott (1983), Nogueira (1991), and John & Tsarenko (2002).Fuentes et al. (2010) and Santana (2011) reported the occurrence of M. kormakovae in Bahia State from the analysis of material from the Rio de Contas and Almada River, respectively.However, the authors did not provide descriptions or illustrations of the materials that were identified, thereby preventing the restudy of the species.Therefore, we consider the present study to be the first confirmed report of the occurrence of this species in Bahia State.Hindák, Biol Prace 30 (1): 228, pl. 80, fig. 1. 1984. Figure 3f Cells solitary, fusiform, straight, gradually tapered apices, pointed ends; single parietal chloroplast without pyrenoids.Cell dimensions: 22.5-28 μm in length, 2.5-3.5 μm in width.
Monoraphidium litorale is morphologically close to M. pusillum (Printz) Komárková-Legnerová and M. affixum Hindák, differing from the first by having less tapered apices and generally longer cells and differing from the second by having smaller and straighter cells.
The populations of M. litorale analyzed in this study agreed with the descriptions and illustrations reported by Hindák (1984) and John & Tsarenko (2002).
The first record of this species for Brazil appears in Nogueira (1999) from material collected in a Samambaia reservoir, located at the Universidade Federal de Goiás (UFG), Goiás State, but the cell dimensions presented by this author are smaller than those found in the specimens from the Pantanal dos Marimbus.
This report constitutes the first citation of the species for Northeastern Brazil.
According to its morphological features, Monoraphidium minutum is close to M. nanum (Ettl) Hindák; however, this species is distinguished by having smaller cell dimensions and cells with a smaller degree of curvature.It is similar to the solitary cells of Kirchneriella Schmidle but differs by having cells surrounded by a sheath of mucilage.
The populations studied were slightly larger than those described by Komárek (1983) and Comas (1996), although they are within the metric limits referred to by Komárek & Fott (1983), Nogueira (1999), andJohn &Tsarenko (2002).Menezes et al. (2012) and Santana (2011) reported the occurrence of M. minutum in Bahia State; however, the authors did not present descriptions or illustrations of the material to allow us to compare them to the specimens studied here.Therefore, we consider the present study to be the first confirmed report of the occurrence of this species in Bahia State.
The specimens studied had slightly larger cell than those described by Komárek & Fott (1983) and Comas (1996).
The first reference to M. pusillum in Bahia State is in Menezes et al. (2012), but the authors did not provide description or illustration of the material that would allow us to restudy the taxon.Therefore, we consider the present study to be the first confirmed report of the occurrence of these species in Bahia State.
The populations from Bahia State that were analyzed in this study agreed with the descriptions and illustrations by Komárek & Fott (1983), John &Tsarenko (2002), andFerragut et al. (2005).
This report constitutes the first citation of the species for Northeastern Brazil.
The taxonomic inventory conducted at the two areas of the Pantanal dos Marimbus (Baiano and Remanso) recorded the occurrence of 18 taxa, 13 of Monoraphidium and five of Ankistrodesmus.
Of the total taxa studied, eight are cited for the first time in Northeastern Brazil: Ankistrodesmus bernardii, A. densus, A. falcatus, Monoraphidium caribeum, M. circinale, M. dybowskii, M. litorale, and M. tortile, as well as Ankistrodesmus spiralis is an addition to continental microalgae flora of Bahia State.
During the analysis of the Monoraphidium genus, the main difficulty to identifying certain species (M.arcuatum and M. caribeum) was related to the degree of curvature of the cells, which was sometimes more or less open.In addition, taxa with typically straight cells, such as M. griffthii, sometimes had slightly curved cells.In Ankistrodesmus, the main difficulty in separating the colonies into different groups was in delimiting the taxa because the single cells are usually confused with individuals of Monoraphidium, i.e., cells of A. spiralis that are similar to M. irregulare.However, in both cases, studying the populations was essential for differentiating between the taxa.
The number of species of Monoraphidium identified in the present study was higher when compared with the studies of Ferragut et al. (2005) and Tucci et al. (2006), which cited seven and eight taxa respectively, in the shallow oligotrophic reservoir (lake at IAG) and in the Lago das Garças, both in São Paulo State; Bortolini et al. (2010), who recorded three taxa in the Embrapa Gado de Corte in Mato Grosso do Sul State; and Hentschke & Torgan (2010), who reported four taxa at the Butiazal de Tapes and Lagoa do Casamento in Rio Grande do Sul State.
Comparing the occurrence of species at the two areas in the Pantanal dos Marimbus (Baiano and Remanso), we found that almost all of the taxa were common between the two areas, except for Ankistrodesmus bernardii, which occurred only at Baiano, and Monoraphidium minutum, which only occurred at Remanso.The most representative species in the study area were Monoraphidium griffithii and Ankistrodesmus densus.
This study has expanded the knowledge of the biodiversity of the Ankistrodesmus and Monoraphidium in Bahia State and extends the geographic distribution of these in Northeastern Brazil.Based on the results obtained, the number of taxa recorded for Bahia of the Ankistrodesmus increased from three to five taxa and Monoraphidium from eight to thirteen.
Fuentes et al. (2010) & Menezes et al. (2012) reported the occurrence of M. arcuatum in Bahia State.These authors did not describe or illustrate the morphology of the material studied.Due to the lack of factual information contained in these studies, the reports byFuentes et al. and  by Menezes et al. were discarded, and the present study is considered as a pioneer in Bahia State.