Taxonomy and ecological distribution of the genus Microspora (Microsporaceae, Chlorophyta) in lotic ecosystems of São Paulo State, southeastern Brazil

Abstract

Occurence of populations of the genus Microspora was investigated in 172 stream segments, which were sampled from May to October in 1992-1993 and 1996-1997 in six natural regions (parts of biomes or geological areas) of Sao Paulo State, southeastern Brazil. Three species were recognized, distinguished on the basis of shape and size of vegetative cells, H-shaped cell wall pieces and presence of rings in transverse cell walls. M.floccosa had cells with larger diameter (> 9.5 μm) and H-shaped structures clearly discernible throughout the filament lenght. M. quadrata and M. stagnorum had cells with smaller diameter (≤ 9.5 μm), the former with straight inner corners and the latter with rounded inner corners. H-pieces were discernible throughout the filament length in M. quadrata, whereas in M. stagnorum they were more clearly distinguishable at the terminal cells of the filament. In addition, the transverse cell walls of M. stagnorum had reddish to brownish rings. In comparison to macroalgal communities as a whole, the genus Microspora occurred under similar mean values of temperature (19.7 x 19.6 °C, respectively), specific conductance (72 x 69 μS cm -1 ), turbidity (8 x 9 NTU) and pH (6.9 x 6.8) but higher current velocity (48 x 63 cm s -1 ) and lower oxygen saturation (66 x 58 %). Trends for occurrence of individual species were considerably variable around these values. In terms of species occurrence in the regions of Silo Paulo State, the species of Microspora showed a relatively restricted distribution: M. floccosa occurred in only 9 sampling sites of three regions, whereas M. quadrata and M. stagnorum were present in only 3 sites of two regions. The three species were previously reported in boreal, temperate and tropical regions of the world.