Ascosporogenesis in Tarzetta (Otideaceae, Pezizales)

Ascosporogenesis in Tarzetta is, in many respects, very similar to that of other discomycetes in the Pezizaceae, Helvellaceae, and Morchellaceae. Ther e is, however, no condensation of globular secondary wall material within t he perisporic sac, a condition similar to the type of secondary wall format ion observed in Pulvinula and Geopyxis (Otideaceae). Two stages in the spor e ontogeny of Tarzetta are very distinct from spore ontogeny in other Peziz ales: (i) epispore is formed without inclusion of spinelike precursors but instead with interconnecting periclinal fragments, and (ii) an electron-opa que primary wall (or initial wall) is deposited between two spore-delimitin g membranes. These features of spore ontogeny suggest that Tarzetta may not be as closely related to other genera of Otideaceae, where it has been tra ditionally placed.