Freshwater Ascomycetes: Isthmosporella pulchra gen. and sp. nov.

A new freshwater ascomycete isolated from submerged wood in New York is des cribed as a new genus and species in the Phaeosphaeriaceae, Pleosporales. T his species has globose, pseudoparenchymatous ascomata, sparse, septate pse udoparaphyses, fissitunicate asci and hyaline, cylindrical to fusoid, phrag moseptate, isthmoid ascospores. The ascospores are distinctive from those o f other genera in the Phaeosphaeriaceae in having a central two-celled isth mus. In addition, the ascospores are surrounded by a gelatinous sheath that expands in water, a feature characteristic of many aquatic ascomycetes.