Psiloglonium Höhn., Ann. mycol. 16(1/2): 149 (1918).
Index Fungorum number: IF 4507; Facesoffungi number: FoF 08062, 16 morphological species (Species Fungorum 2022), 7 species with molecular data.
Saprobic on decaying wood. Sexual morph: Ascomata hysterothecial, scattered, superficial, base immersed in the substrate, elongate and depressed conchate, globose, surface black, shiny, longitudinally striate, apex compressed, opening by a longitudinal slit. Peridium carbonaceous, brittle, comprising heavily pigmented, small, prosenchymatous cells. Hamathecium comprising 0.5–1 μm wide, hyaline, aseptate, branched, trabeculate pseudoparaphyses, in a gelatinous matrix. Asci bitunicate, 8-spored, oblong to clavate, with a very short pedicel or apedicellate, apically thickened, with a distinct ocular chamber. Ascospores crowded to biseriate, fusiform when young, oblong at maturity, hyaline when young and becoming brown at maturity, smooth-walled, ornamented, surrounded by a mucilaginous sheath. Asexual morph: Unknown (adapted from Li et al. 2016).
Type species: Psiloglonium lineare (Fr.) Petr.
Notes: Höhnel (1918) initially revised Glonium as composed of two different morphological types, and separated Glonium and Psiloglonium based on the presence or absence of subicula. Petrak (1923) pointed out that Höhnel (1918) had introduced Psiloglonium both at sub-generic and generic rank. Petrak (1923) selected the type species for Psiloglonium as P. lineare and accepted G. stellatum as the type species for Glonium sensu Höhnel (1918). Lohman (1933, 1937) did not accept Psiloglonium as a distinct genus from Glonium based on the similar asexual morphs morphology. Zogg (1962) synonymized several Psiloglonium taxa under the genus Glonium. Zogg (1962) also noted that some taxa previously accommodated in Psiloglonium do have subicula and hence did not consider subicula as a synapomorphic character and transferred those taxa namely P. finkii, P. lineare, P. microspermum and P. ruthenicum to Glonium. Zogg (1962) also reported three morphological types in Glonium, (Types I and II) which Boehm et al. (2009) incorporated in Psiloglonium and the third (Type III) which forms the basis for Gloniaceae. Arx and Müller (1950, 1975) considered Psiloglonium as a synonym of Glonium. Barr (1987) retained Psiloglonium as a distinct genus from Glonium. Boehm et al. (2009) re-instated Psiloglonium within the Hysteriaceae to accommodate taxa with apically obtuse didymospores. Boehm et al. (2009) provided eight new combinations for the genus Psiloglonium, to accommodate taxa initially classified under Glonium in Gloniaceae. Liu et al. (2015) added a new species, P. multi-septatum based on morphological and phylogenetic evidence. Currently, Psiloglonium is morphologically and phylogenetically a distinct genus in Hysteriaceae. Molecular markers available for Psiloglonium are ITS, LSU, SSU, RPB2 and TEF-1.