Acrochaete marchantiae comb. nov. and Trichothyra irregularis gen. et sp. nov. with notes on other species of small filamentous green algae from St. Lucia (West Indies)

Nine species of small, filamentous green algae were identified from St. Lucia, in the Lesser Antilles. Observations were made on field-collected material and isolates obtained in unialgal culture. Acrochaete marchantiae (Setchell & Gardner) comb. nov. has been transferred from Pringsheimiella marchantae Setchell & Gardner. Trichothyra irregularis is described as a new genus and species, Blastophysa arrhiza Wille and B. polymorpha Kjellman are considered synonyms of B. rhizopus Reinke, and Phaeophila polymorpha Jao is considered synonym of P. dendroides (Crouan) Batters. These species were associated with a wide variety of substrate, including other algae, corals, rocks, and wood, with little apparent host specificity. All of the species recorded are new records for St. Lucia and five species are new records for the Caribbean.