Ultrastructural Investigation of Humariaceae (Pezizales, Ascomycetes). II. Ascosporogenesis in Selected Genera of the Ciliarieae

Species of Cheilymenia, Coprobia, and Scutellinia of the Ciliarieae (Humariaceae) are studied by electron microscopy. They share the same type of ascosporogenesis, although only Cheilymenia and Coprobia form spore sheaths on their ascospores, and epispore layers are formed after the primary wall is deposited between spore-delimiting membranes. The manner of formation of epispore layers is very similar to that in the genus Aleuria. Gradual condensation of the secondary wall material in the perisporic sac is consistently found. Globular bodies with rodlet contents are found in the perisporic sac of Cheilymenia and are different from those found in Aleuria. Vacuolation occurs in the perisporic sac, within which ornaments are almost completely formed. During the condensation of secondary wall material, a translucent zone similar to that commonly found in Ascobolus and other coprophilous fungi is formed between the epispore layer and the ornaments.