Cryptic diversity in Tranzscheliella spp. (Ustilaginales) is driven by host switches

Species of Tranzscheliella have been reported as pathogens of more than 30 genera of grasses (Poaceae). In this study, a combined morphological and molecular phylogenetic approach was used to examine 33 specimens provisionally identified as belonging to the T. hypodytes species complex. The phylogenetic analysis resolved several well-supported clades that corresponded to known and novel species of Tranzscheliella. Four new species are described and illustrated. In addition, a new combination in Tranzscheliella is proposed for Sorosporium reverdattoanum. Cophylogenetic analyses assessed by distance-based and event-cost based methods, indicated host switches are likely the prominent force driving speciation in Tranzscheliella.