Megaspora is a genus of lichen-forming fungi in the family Megasporaceae. It contains four species of crustose lichens that typically grow on soil, bryophytes (mosses and liverworts), or plant litter on chalky .
The genus was circumscribed by Georges Clauzade and Claude Roux in 1984 with M. verrucosa assigned as the type species.
In 2012, Linda in Arcadia and Anders Nordin proposed to conserve the name Megaspora verrucosa against M. verrucosa due to taxonomic confusion stemming from historical errors in the original basionym citation. The original introduction of Aspicilia subg. Megaspora erroneously cited Lecanora verrucosa as the basionym, when it should have been Urceolaria verrucosa This misattribution led to the invalid introduction of the name Megaspora verrucosa by Hafellner & Wirth based on the wrong species. To rectify this and prevent future taxonomic issues, the proposal suggested adopting M. verrucosa based on U. verrucosa as the conserved name, which the Nomenclature Committee for Fungi eventually recommended accepting after initially considering rejection.
Megaspora is a genus of crustose lichens, meaning they form a crust-like growth on their substrate. The thallus (lichen body) is non- (lacking distinct lobes) and can appear somewhat powdery . The, or photosynthetic partner, in this lichen is, referring to a type of green algae.
The reproductive structures of Megaspora are apothecia, which are deeply immersed in the (small, wart-like structures on the thallus). The apothecia have a, a rim composed of thallus tissue. The, or the outer layer surrounding the apothecia, is thin and either colourless or pale straw-coloured, consisting of tightly packed, vertically aligned hyphae (fungal filaments).
The, the uppermost layer of the apothecium, is brown-green and turns bright green when treated with a nitrogen-based reagent (N+). The hymenium, the spore-bearing layer, is colourless and turns blue with iodine (I+). The, the layer beneath the hymenium, is also colourless. The, which contains the paraphyses (sterile filaments among the asci), is richly branched and interconnected (anastomosing) without swollen tips, and is strongly d (stuck together).
The asci (spore-producing cells) are of the Biatora-type, containing 4 to 8 spores, and are (club-shaped) or cylindric-clavate, with thin walls except towards the apex. The asci have a pale (a thickened area at the tip) that reacts faintly with potassium/iodine (K/I). The are large, aseptate (without internal divisions), globose (spherical) to shortly ellipsoidal, colourless, and have uniformly thickened walls.
Conidiomata (structures producing asexual spores) have not been observed in this genus. No lichen products have been detected through thin-layer chromatography.
Megaspora lichens typically grow on soil, bryophytes (mosses and liverworts), or plant litter on calcareous (chalky) substrates. They are rarely found growing on bark (corticolous).