Heterothalic mating systems in the Echinosteliales II. Echinostelium coelocephalum

Seventeen Echinostelium coelocephalum cultures were isolated from cholla ca ctus and desert holly detritus collected in Death Valley National Park, Cal ifornia, and near Tucson, Arizona. All 17 isolates are heterothallic diploi ds and possibly belong to a single multiple allelic mating series. Two sepa rate multiple allelic series of 13 and 4 isolates were identified but could not be tested against each other due to the loss of cultures in the latter series. Nine mating types were detected in 5 of the 13 isolate series (exa ct mating type designation could not be provided for the remaining 8 isolat es) and 8 mating types were found in the separate 4 isolate series. Several of the isolates were found to have high levels of intraisolate crossing st erility however, these apparently sterile clones were generally capable of interisolate crossing to clones having different mating types.