ISOZYME PATTERNS IN CULTURED HARPELLALES

Trichomycetes (Zygomycota) are arthropod-associated fungi consisting o f three orders, only one of which, the Harpellales, contains cultured species. Isozyme patterns were studied using starch gel electrophoresi s of 108 isolates representing 18 described species from six genera of Harpellales (Capniomyces, Furculomyces, Genistelloides, Simuliomyces, Smittium, and Trichozygospora), and some undescribed species of Smitt ium, as well as three isolates of Amoebidium parasiticum (Amoebidiales ) and three species of nontrichomycetous fungi. A total of 176 differe nt band positions for 13 loci in 11 enzyme systems were produced. The banding patterns were consistent with haploidy. Numerical taxonomic an d principal coordinate analyses of Trichomycetes compared isozyme vari ation within and among described and undescribed species, including th ree named isolates of uncertain identity. There was no discernible pat tern among the cultures attributable to geographic origin or type of i nsect host family. Isolates of described species produced similarity c lusters that generally correlated well with morphologically defined ge nera and species. Based on isozyme patterns, one isolate tentatively i dentified as G. hibernus was re-examined and reclassified as C. stella tus. Thirty-six undescribed isolates of Smittium produced seven cluste rs that probably represent new species. Other undescribed Smittium iso lates grouped with described species and may be conspecific. Copheneti c correlation coefficients for 13 clusters of Harpellales species were greater than or equal to 0.90, but for A. parasiticum it was only 0.8 7; the latter may represent a species complex. Thirty-two isolates of Sm. culisetae originating from France, Australia, Japan, and six USA s tates (including Hawaii) were isozymically very similar or identical t o each other, despite differences in their geographic origins and dipt eran host families. A phenogram based on isozyme patterns generally co rresponded with one from a previous immunological study.