FRESH-WATER EPIPHYTIC CYANOPROKARYOTES FROM CENTRAL MEXICO .3. THE GENUS STICHOSIPHON-GEITLER 1932

This is the third study on the cyanoprokaryotic (cyanophycean, cyanoba cterial) epiphytes, colonizing submersed substrates (mainly other fila mentous algae) in streaming waters in central Mexico. The species of t he genus Stichosiphon GEITLER 1932 were all made synonyms of S. sansib aricus by DROUET & DAILY (1956). We have found six morphotypes, which can be distinguished at the species level, five corresponding to speci es defined by previous authors and one new species, S. exiguus. The mo rphological variation of the Mexican populations was studied, and the comparison with the original descriptions of type specimens is present ed. The characters applied in the taxonomy of the genus Stichosiphon a re discussed. One other species, known from Burma (SKUJA 1949), was re defined according to the present diacritical features for this genus ( S. skujae).