New aerophytic morphospecies of Cyanobacteria from tropical forest fragments in northwestern São Paulo state , Brazil

(New aerophytic morphospecies of Cyanobacteria from tropical forest fragments in northwestern São Paulo state, Brazil). Algae and Cyanobacteria can colonize a wide variety of terrestrial environments and the assemblages from aerophytic habitats are very poorly known. During the survey of aerophytic algal and cyanobacterial communities in forest fragments in northwestern São Paulo state, six cyanobacteria populations could not be identifi ed at species level and, after morphological and metrical analysis, proved to be new morphotypes to Science. Four belong to the genus Aphanothece (A. excentrica, A. coacervata, A. densa and A. vaginata), one to Phormidium (P. arboricola) and one to Hapalosiphon (H. santannae). This study presents the description, comparison and proposition of the new morphospecies and improves taxonomic knowledge of the diversity of the group.


Introduction
Algae and cyanobacteria can colonize a wide variety of terrestrial environments, including rocks (Büdel et al. 2002), soil (Evans & Johansen 1999), walls (Rindi & Guiry 2004) and tree trunks (Hoffmann 1989).Cyanobacteria are especially common in terrestrial environments and have important ecological functions in the ecosystem, acting to retain silt and clay and adding large amounts of organic carbon and nitrogen to the soil (De 1939;Fletcher & Martin 1948;Allen 1956;Singh 1961;Whitton 2000), among other properties.However, despite their ecological relevance, taxonomic studies on this group are scarce in the world and most of these focus mainly on edaphic organisms (Johansen 1993;Flechtner et al. 1998;Tirkey & Adhikary 2006).
Taxonomic knowledge concerning cyanobacteria from terrestrial habitats in Brazil is very limited.Studies regarding the edaphic community from Rio de Janeiro and São Paulo states were presented by Oliveira (1976) and Oliveira et al. (1980).Azevedo (1991), in a study of the edaphic cyanobacterial community of the São Paulo Botanical Garden, found 24 specific taxa distributed in nine families and described a new species of Lyngbyopsis.
Some surveys provide additional information on cyanobacteria from other terrestrial habitats.The study carried out by Sant'Anna (1984) investigated the cyanobacterial fl ora associated with bryophytes in Campina Grande (Minas Gerais) and recorded 23 species from fi ve different families.Sant'Anna et al. (1991a) described a new species of Gloeothece from "Grutaque-chora" at Sununga beach (Ubatuba, São Paulo).In addition, the aerophytic cyanobacterial fl ora of the same locality was surveyed by Sant'Anna et al. (1991b) and resulted in the identifi cation of 41 specifi c taxa from 11 families, including two new species of Calothrix.Büdel et al. (2002) carried out an investigation on the cyanobacteria from inselbergs in the Atlantic forest (eastern Brazil) and found 16 species.
Recent data on aerophytic cyanobacterial fl ora indicate that knowledge of diversity in the Brazilian territory is still underestimated (e.g., Branco et al. 2009).In addition, new aerophytic morphospecies have been described for different regions of São Paulo state comprising three new Symplocastrum (Branco et al. 2006a), one new Cyanoarbor (Branco et al. 2006b)

Material and methods
Sampling was carried out between March and May, 2007, in seasonal semideciduous forest fragments occurring in northwestern São Paulo state (Tab.1).
Detailed description of collection, preservation and study can be found in Lemes-da- Silva et al. (2010).In short, visible growths of algae, cyanobacteria and bryophytes were collected from randomly selected tree bark.The dried material was taken to the laboratory, rehydrated and analyzed under stereoscope microscope and light microscope.For each population found, at least 20 observations of each qualitative or quantitative taxonomic characteristic were made.
The taxa found were described according to the patterns adopted for each group and the following abbreviations were used for species description in text and tables: diam.(diameter) and L/D (cell length/diameter ratio).

Results and discussion
Six new morphospecies of cyanobacteria, belonging to the orders Chroococcales (Aphanothece excentrica, A. coacervata, A. densa and A. vaginata) Etymology: The specifi c epithet refers to cell arrangement, which is densely aggregated in the whole colony.
Occurrence: S3.Comments: The species most similar to Aphanothece coacervata is A. saxicola Nägeli, since they have close cell-length metrics (Tab.2).However, A. saxicola usually forms macroscopic and amorphous colonies and typical cells are smaller in diameter (1.0-2.Etymology: The specific epithet refers to cells agglomerated in the center of the colony.Colonies microscopic, spherical; cells densely agglomerated in the center of the colony; colonial sheath yellowish brown, margin well delimited and wide; cells cylindrical, 4.0-7.0μm long, 4.0-5.0μm diam., L/D 1.0 to 1.7; cell content homogeneous, blue-green.
According to Komárek & Anagnostidis (1998), A. variabilis presents densely agglomerated cells, as well as A. densa; however they are distinguishable by the longer cells (4.2-10.0μm) and habitat (marshes and reservoirs) of   Comments: This population presents metrics similar to Aphanothece pallida (Kützing) Rabenhorst (Tab.4), however the cells are distributed along the colony margin and each one is surrounded by an individual concentrically lamellate sheath in the latter, while in A. excentrica the individual sheath is asymmetrical and granular, when present.An additional morphological incompatibility between the two taxa is the presence of greenish to brownish sheath in A. pallida and colorless in A. excentrica.The two species are also ecologically distinguishable since A. pallida is typically a soil-andwet-walls inhabitant and A. excentrica was found on tree Etymology: The specifi c epithet refers to colonial sheath with well-delimited margin.
Occurrence: S3.Comments: Aphanothece vaginata is close to A. castagnei (Brébisson) Rabenhorst (Tab.5).According to Komárek & Anagnostidis (1998), colonies of A. castagnei are macroscopic and irregularly spherical to amorphous and the cells, with individual lamellate and yellowish brown envelopes, are distributed along the colony margin, differing from A. vaginata.Some species of Aphanothece described in this study were found in the same forest fragment but they are clearly separated and recognizable on the basis of their morphology and metrics (Tab.6).
Etymology: The specific epithet refers to typical habitat (on tree bark) where organisms of this species are found.
C o m m e n t s : P h o r m i d i u m c o r b i e r i ( F r é m y ) Anagnostidis & Komárek and P. ornatum (Kützing ex Gomont) Anagnostdis & Komárek are the species most similar to the Brazilian populations (Tab.7).They have cell diameter similar to that o f Phormidium arboricola, however both species are found in periphyton of European environments, signifi cantly differing from the studied populations.
Occurrence: L3.Comments: Hapalosiphon fontinalis (Agardh) Bornet has fi lament diameter comparable to Hapalosiphon santannae, however it is found in aquatic environments and has longer than wide cells (Tab.8).
In the most extensive survey of true-branched Nostocales carried out in São Paulo state, Silva & Sant'Anna (1990) found six species of Hapalosiphon, all occurring in aquatic environments, except for H. stuhlmannii Hieronimus that was also found growing on wet rocky wall and soil, but with different fi lament diameter ((4.0-)5.9-11.5 (-14.3)μm) than Hapalosiphon santannae.Azevedo et al. (1996) recorded H. stuhlmannii in edaphic environment in São Paulo state; however the morphological and metric characteristics differ from those of Hapalosiphon santannae (Tab.8).The taxonomic knowledge of aerophytic cyanobacterial communities is proved to be insuffi cient to offer a solid background on biodiversity patterns, especially in tropical regions.Ideally, molecular approaches are recommended to better characterize the species but aerophytic cyanobacteria are diffi cult organisms to cultivate and, consequently, the characterization of the populations from nature is still an important step in the recognition of the specifi c tropical fl ora and for understanding cyanobacterial diversity in different ecosystems and regions (Komárek & Komárková-Legnerová 2007;Sant'Anna et al. 2007).It is hoped that studies dealing with aerophytic cyanobacterial communities are encouraged to provide a good basis for group taxonomy, phylogeny and diversity.

Table 1 .
Locality and total area of forest remnants where the new morphospecies were found.(L -large area, S -small area).

Table 6 .
Comparison of morphometric characteristics of the Aphanothece found species.