Molecular Variation within and among Species of Harpellales

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