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. There is, however, no condensation of globular secondary wall material within the perisporic sac, a condition similar to the type of secondary wall formation observed in Pulvinula and Geopyxis (Otideaceae). Two stages in the spore ontogeny of Tarzetta are very distinct from spore ontogeny in other Pezizales: (i) epispore is formed without inclusion of spinelike precursors but instead with interconnecting periclinal fragments, and (ii) an electron‐opaque primary wall (or initial wall) is deposited between two spore‐delimiting membranes. These features of spore ontogeny suggest that Tarzetta may not be as closely related to other genera of Otideaceae, where it has been traditionally placed.