Polyphyly of intraspecific groups of Umbelopsis ramanniana and their genetic and morphological variation

Abstract

The taxonomic positions of three intraspecific groups of Umbelopsis ramanniana in the genus Umbelopsis were analyzed based on the nucleotide sequences of their nuclear large subunit ribosomal DNA (nLSU rDNA) D1/D2 region. The examined members of the genus Umbelopsis were resolved into two major clades, Clades I and II. The intraspecific groups of U. ramanniana were nested within Clade II together with U. westeae, U. swartii, U. autotrophica, U. gibberisopra, U. angularis, and U. fusiformis. In this major clade, the intraspecific groups of U. ramanniana were split into three polyphyletic subclades. This suggests that U. ramanniana is an assemblage of several genetically distinct species. Interestingly, in spite of the diverse sporangiospore shapes of the members of Clade II, the genetic variation among them was small. It is considered that their flexible sporangia membranes make it possible for them to develop various sporangiospore shapes.