Floristics of epiphytic diatoms in a patch of subtropical macroalgae.

Abstract

The species composition of epiphytic diatom assemblages found on different taxa of subtropical macroalgae was determined. Samplings were carried out in a macroalgae bed located in Punta Roca Caimancito beach, B. C. S. in june and december 2001, and on april, may and july 2002, collecting the most frequent macroalgae taxa. The most conspicuous out of twelve macroalgae taxa were: Hydroclathrus clathrathus, Laurencia pacifica, L. johnstonii, Padina mexicana and P. caulescens. A total of 278 diatom taxa were recorded. This is the largest species richness recorded for this type of substrate, and out of which 44 are new records for the region. Out of 75 genera recognized the best represented were: Mastogloia (25 species), Amphora (23), Navicula (23), Nitzschia (22), Cocconeis (22), Lyrella (12) and Achnanthes (11). The most abundant taxa were Cocconeis disculus and C. dirupta. The number of diatom taxa permacroalgae species was also high, ranging from 89 (Codium spp.) to 143 (L. pacifica). Albeit, this differencecould be attributed to the number of specimens collected per macroalga species.