The Didymosporous Dimeriaceous Fungi Described on Asteraceae

SUMMARY

Dimeriella and Epipolaeum species occurring on Asteraceae (Compositae) are described, illustrated, and reclassified. Dimeriella is removed from the Dimeriaceae mainly because of centrum structure of the type species, D. hirtula. Lasiostemma, formerly considered a synonym of Dimeriella and Wentiomyces, is resurrected. The type species of Epipolaeum, E. irradians, is shown to belong in Lasiostemma, which has nomenclatural priority. The other species of Dimeriella and Epipolaeum are transferred either to Lasiostemma or Eudimeriolum, according to presence or absence of a hyphal layer in the matrix. On the basis of presence or absence of setae on the ascocarp, Lasiostemma is subdivided into subgenera Lasiostemma and Setostemma, and Eudimeriolum into subgenera Eudimeriolum and Setocarpum. A new species, Eudimeriolum hirtuloides, is described. Two previously studied species of Dimeriella on Poaceae are transferred to Eudimeriolum and one to Lasiostemma. Epipolaeum petastidis is reclassified in Coleroa (Stigmateaceae). Dimeriella cordiicola, on boraginaceous hosts, is shown to be conspecific with D. claviseta.