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

Abstract

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 Powellomyces-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. I sequenced portions of nucSSU and nucLSU rDNA regions and the EF-1α-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 ultra-structural 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.

• chytrid
• Chytridiomycetes
• EFL
• nucLSU rDNA
• nucSSU rDNA
• Spizellomycetales
• zoospore ultrastructure

ACKNOWLEDGMENTS

I thank JE Longcore for indispensable training, assistance and review. I thank PM Letcher, KT Picard and MJ Powell for cultures and helpful discussions. I thank K Edwards of the Electron Microscopy Laboratory and D Cox and P Singer of the DNA Sequencing Facility at the University of Maine for their training and services. I thank T Passman of the University of Maine Department of Modern Languages and Classics for providing Latin translations of taxonomic descriptions. I thank two anonymous reviewers for their comments and suggestions.

This study was financially supported by the NSF DEB grant PEET 0529694.