Ultrastructural observations on Helvellaceae (Pezizales, Ascomycetes). V. Septal structures in Gyromitra

Abstract

Ultrastructure of septa in asci, ascogenous hyphae, paraphyses, and excipular cells in selected species of Gyromitra is described. Electron-opaque, conical structures are found in the basal pores of young asci and with age bear V-shaped striations. In certain species, the pore plug is overgrown by secondary wall material. Pores of the ascogenous hyphae have a matrix of electron-dense material with a very dense zone of material around the border of the pore. Septal pores of paraphyses and excipular cells have extremely elongate, rectangular Woronin bodies in the surrounding cytoplasm. Internal striations within these bodies suggest a proteinaceous nature. Pores of the paraphyses and excipular cells may also become occluded with a matrix of electron-dense material often with striations referred to as laminate structures. Septal structures in the species of Gyromitra investigated are compared to those of Helvella and members of other families of Pezizales. Phylogenetic implications of these data are discussed. © 1991, British Mycological Society. All rights reserved.