Resurrection of Blistum tomentosum and its exclusion from Polycephalomyces (Hyphomycetes, Deuteromycota) based on 28S rDNA sequence data

Members of the form genus Polycephalomyces (Hyphomycetes, Deuteromycota) were morphologically and phylogenetically evaluated. The aberrant taxon P. tomentosus was earlier placed in Blistum, for which it was the type. Blistum was distinguished from other Hyphomycetes on the production of white synnemata, ornamented cells along the synnemous stipe, viscous conidial mass at synnemous apex and a myxomyceticolous habit. Observations of Polycephalomyces species revealed that P. tomentosus can be distinguished from other spedes in the genus by its myxomyceticolous habit, verrucose ornamented cells along the synnemous stipe, and production of conidia that are variable in size (2.4-7.6 x 1.6-3.2 μm) and shape (ovoid, broadly fusiform and subglobose). Phylogenetic analyses of 28S rDNA excluded P. tomentosus from the clade containing all other Polycephalomyces species, thus making the genus paraphyletic. However, all Polycephalomyces species were recovered in the Clavicipitaceae clade when analyzed using either Hypocreaceae or Nectriaceae as outgroups. Therefore, we have segregated P. tomentosus from Polycephalomyces and again classified it n the monotypic genus Blistum.