Septal Structures in Apothecial Tissues of Taxa in the Tribes Scutellinieae and Sowerbyelleae (Pyronemataceae, Pezizales, Ascomycetes)

Septal pore structures are described in asci, ascogenous hyphae, paraphyses, and excipular cells of species of Cheilymenia and Scutellinia (tribe Scutellinieae), and Acervus and Caloscypha (tribe Sowerbyelleae) of the Pyronemataceae. The ascus pore plugs of Cheilymenia and Scutellinia begin as a single electron-opaque band across the pore but develop into banded hemispherical structures within the ascus. Ascus pores of Acervus and Caloscypha are filled with an electron-opaque matrix in young asci, but by maturity they are plugged by a hemispherical, electron opaque structure with membranelike, translucent borders. Pores of the ascogenous hyphae of Cheilymenia and Scutellinia are occluded by Woronin bodies covered by deeply staining amorphous material. Plugging of ascogenous hyphal pores in Acervus and Caloscypha is similar to that of their asci. Lamellate structures are found in the pores of excipular cells in all species studied.Structure and development of septal pore organelles in Acervus and Caloscypha are very similar to those found in members of the tribe Aleurieae but differ significantly from those of the Scutellinieae. Comparisons of pore structures of these two tribes are made with those of the Pezizaceae and Asco-bolaceae. The taxonomic and phylogenetic significance of these data is discussed.