Acanthostigma De Not., Hedwigia 4: 28 (1865).
Saprobic on dead plant debris. Sexual morph: Ascomata superficial, scattered, globose to subglobose, reddish-brown to dark brown, collapsing when dry, sparsely setose on the upper part, setae dark brown to opaque. Peridium consisting of several-layers of polyhedral cells. Hamathecium composed of numerous, cellular, branched and anastomosing pseudoparaphyses developing from the basal hymenium. Asci 8-spored, bitunicate, fissitunicate, clavate, broadly rounded and thickened at the apex, short-pedicellate. Ascospores fusiform, narrowly rounded at both ends, one of middle cells often broader than the others, trans-septate, straight or slightly curved, not-constricted or slightly constricted at the septa, hyaline. Asexual morph: Unknown (adapted from Boonmee et al. 2011).
Type species: Acanthostigma perpusillum De Not
Notes: Acanthostigma was revised by Réblová and Barr (2000) and the type was re-described by Berlese (1893). Acanthostigma is characterised by superficial, scattered, globose to subglobose ascomata, clavate, broadly rounded asci and fusiform, hyaline ascospores narrowly rounded at both ends. Acanthostigma is morphologically and phylogenetically a distinct genus in Tubeufiaceae. Molecular markers available for Acanthostigma are ITS, LSU, SSU and RPB2. For synonyms see Species Fungorum (2023)