Molecular variation within and among species of Harpellales

Intra- and interspecific variation of the nuclear ribosomal internal transc ribed spacers (ITS) of 77 Smittium isolates and related genera tvas studied using RFLP. Due to the sequence and length variation encountered, the ITS is unsuitable for comparison at the species level within Smittium, as prese ntly delimited. Intra- and interspecific variation of 18S rDNA was also ana lyzed. Cladistic analysis of 32 new 18S rDNA sequences resolved at least fi ve lineages and suggests that Smittium is not monophyletic. In addition, 17 18S rDNA sequences from 5 orders of Zygomycota were included to assess phy logenetic relationships with the Trichomycetes. The kickxellid origin of Tr ichomycetes was not strongly supported.