Asci of the Pezizales III: The Apical Apparatus of Eugymnohymenial Representatives

Abstract

Morphological, developmental and cytochemical examinations were made with light and electron microscopy on the apical apparatuses of four eugymnohymenial species, Pyronema domesticum, Ascodesmis sphaerospora, Coprotus winteri and C. lacteus. Ascal tips in all four species were notably thinner walled than the rest of the ascus. Ultrastructurally, demarcation of the opercula was enhanced after staining with silver methenamine. Wide zones of dehiscence are formed in the outer layer of A. sphaerospora and C. winteri. In P. domesticum the outer layer of the operculum is differentially stained from the rest of the ascal wall. Wall dimensions in the multispored asci of C. winteri are approximately three times greater than those in the eight-spored asci of C. lacteus. The shape of the apical apparatus of C. lateus is almost identical to that of C. winteri. Morphological and cytochemical similarities of the apical apparatuses in Ascodesmis, Pyronema and Coprotus help demonstrate greater relationship between these taxa and support the belief that these taxa are most closely related to members of the Otideaceae and Aleuriaceae.