Sampling for chytrids in a variety of habitats has resulted in pure cultures that when analyzed have yielded hypotheses of relationships based on molecular and zoospore ultrastructural markers. To extend our understanding of diversity of Chytridiales in eastern Argentina and USA, we isolated and examined the morphology, ultrastructure and 28S and ITS1-5.8S-ITS2 rDNA sequences of numerous chytrids from aquatic habitats from these two regions. Three family-level lineages (Chytridiaceae, Chytriomycetaceae, family incertae sedis) are represented in our molecular phylogeny, and three new genera (Avachytrium, Odontochytrium in Chytriomycetaceae, Delfinachytrium in family incertae sedis) are described. These findings of new genera and species emphasize the potential for discovery of additional diversity.
Keywords: chytrid; morphology; phylogeny; systematics; ultrastructure; zoospore.