Heterothallism in the Microascaceae demonstrated by three species in the Scopulariopsis brevicaulis series

Scopulariopsis anamorphs are known for many species of the genus Microascus (Ascomycota, Microascaceae), but teleomorph connections for anamorphic spe cies within the 'Scopulariopsis brevicaulis series' are tenuous or lacking. Microascus brevicaulis was recently described as the teleomorph of the typ e and commonest species, S. brevicaulis, but only a few isolates yielded fe rtile perithecia. To investigate whether paucity of sexual reproduction was the result of heterothallism, mating experiments were conducted among isol ates representing the species S. brevicaulis, S. candida, S. asperula, S. f usca and S. koningii. Results demonstrated heterothallism within three spec ies and confirmed that two taxa could be reduced to synonymy. Three holomor ph species, M. brevicaulis, M. manginii, and M. niger, are recognized to in clude anamorphs S. brevicaulis (synonym S. koningii), S. candida, and S. as perula (synonyms S. arnoldii, S. bestae, S. fusca, and S. roseola), respect ively. Microascus niger is redescribed and a neotype proposed. The three sp ecies are most readily recognized by colony color (sandy tan to avellaneous in M. brevicaulis, white to cream in M. manginii, and medium to dark fusco us brown in M. niger). These colonial distinctions correlate generally with conidia that are coarsely roughened, smooth, or finely roughened, respecti vely. However, conidium ornamentation, previously considered a reliable tax onomic character, is shown to be variable.