Phylogeny of Powellomycetaceae fain. nov and description of Geranomyces variabilis gen. et comb. nov.

The genus Powellomyces was described to accommodate two monocentric chytrid species from soil that develop exogenously and possess zoosporic ultrastructure similar to other members of the order Spizellomycetales. Despite Powellongces-like chytrids being commonly observed in gross culture, the genus contained only two species. To determine diversity in this group I amassed 49 isolates of Powellomyces-like chytrids, including the cultures upon which species types were based and new isolates from pollen-baited water cultures of soils, plant detritus and manure. sequenced portions of nucSSU and nucLSU rDNA regions and the EF-1 alpha-like gene from each isolate to produce a molecular phylogeny. This phylogeny supports monophyly of spizellomycetalean chytrids with exogenous development and suggests that multiple distinct lineages exist within this group. This phylogeny, along with a reevaluation of the ultrastructural features of the two described species, supports the recognition of a new family, Powellomycetaceae, and genus, Geranomyces, which contains 31 isolates of G. variabilis comb. nov.