Acanthostigma De Not., Hedwigia 4: 28 .
Index Fungorum number: IF 16; Facesoffungi number: FoF 06813; 41 morphological species (Species Fungorum 2020), 2 species with molecular data.
Type species: Acanthostigma perpusillum De Not., Hedwigia 4: 28 .
Notes: Réblová and Barr (2000) reviewed Acanthostigma and six species were accepted. Boonmee et al. (2011) introduced A. chiangmaiensis based on phylogenetic analyses and morphology. Boonmee et al. (2014b) accepted only A. perpusillum, A. chiangmaiensis, and A. minutum within Acanthostigma, but did not change the status of other Acanthostigma species. The ascomata of Acanthostigma are globose to subglobose, dark brown to black and covered by dark setae, asci are clavate with a short pedicel, and ascospores are broadly fusiform to clavate, with one of the middle cells often broader than others (Boonmee et al. 2011, 2014). Lu et al. (2018b) accepted seven species, A. chiangmaiensis, A. ellisii, A. longisporum, A. minutum, A. patagonicum, A. perpusillum, and A. revocatum.