Intraspecific groups of Umbelopsis ramanniana inferred from nucleotide sequences of nuclear rDNA internal transcribed spacer regions and sporangiospore morphology

Umbelopsis ramanniana is a well-known species in this genus. A characteristic morphological feature of this fungus is the remarkable variation in the sporangiospore shape, which implies the genetic variations occur in the nucleotide sequences of the internal transcribed spacer (ITS) regions of the nuclear ribosomal DNA (nrDNA) in the U. ramanniana isolates. The relationship between the variations of the sequences of the nrDNA ITS regions and those of the sporangiospore morphology was investigated for 12 isolates of U. ramanniana collected in Europe. Neighbor-joining and parsimony analyses on the sequences suggested that these isolates split into three groups. Precise examination of the morphology showed that the isolates of those respective groups were different from each other in their sporangiospore shape. The present study implies at least three intraspecific groups exist in U. ramanniana and that the variations in the nucleotide sequences of the nrDNA ITS regions correlate well with those in the sporangiospore shape in these intraspecific groups.