Phylogenetic divergence of the entomophthoralean fungi: Evidence from nuclear 18S ribosomal RNA gene sequences

Abstract

To analyze the phylogeny and molecular evolution of the entomophthoralean fungi, we determined the small subunit nuclear ribosomal RNA gene sequences for four representative species of the En- tomophthorales and the trichomycete Smittium culi- setae (Harpellales) in the Zygomycota. Ten published reference sequences were added to this analysis. The phylogeny, inferred from the aligned 1480 positions and using the choanoflagellate Diaphanoeca grandis (Choanoflagellida) as an outgroup, divided seven zygomycete species into four clusters. The four species in the Entomophthorales were placed in two clusters, i.e., Basidiobolus ranarum in one cluster containing Chy- tridium, Spizellomyces and Neocallimastix, and the remaining three species Conidiobolus coronatus, Entomo- phthora muscae, and Zoophthora radicans in another cluster containing Mucor. Glomus etunicatum is basal to ascomycetes and basidiomycetes, and Smittium culi- setae was placed close to the divergence of Entomophthorales from the chytrid-GZojrews-ascomycete-basid- iomycete clade. Our analysis also suggests loss of flagella on several lineages in the tree and great phylogenetic divergence among the chytrids.

Key Words:

• chytridiomycetes
• Entomophthorales
• fungal evolution
• lower fungi
• molecular phylogeny
• small subunit rRNA
• zygomycetes