Xenoacrodontium Crous

MycoBank number: MB 841826; Index Fungorum number: IF 841826; Facesoffungi number: FoF12729;

Etymology: Name refers to its morphological similarity to Acrodontium.

Mycelium consisting of hyaline, smooth-walled, branched, septate hyphae. Conidiophores reduced to conidiogenous cells arising directly from hyphae, hyaline, smooth- and thin-walled, subulate, straight to flexuous, proliferating sympodially, forming a rachis in upper part, with multiple subdenticulate loci, slightly thickened and refractive, not darkened. Conidia solitary, hyaline, aseptate, smooth- and thin-walled, guttulate, ellipsoid, with obtuse apex; hilum slightly thickened, not darkened.

Type genus: Xenoacrodontium juglandis Crous .

Notes: Crous et al. (2021) introduced the monospecific genus, Xenoacrodontium in a new family Xenoacrodontiaceae (Hypocreales). Xenoacrodontium is typified by X. juglandis, which has been isolated on Juglans regia (Juglandaceae) from the Netherlands. Xenoacrodontium has smooth-walled, branched, septate hyphae, reduced conidiophores, hyaline, subulate, straight to flexuous, proliferating sympodially, conidiogenous cells arising directly from hyphae with multiple subdenticulate loci, and solitary, hyaline, aseptate, smooth- and thin-walled, guttulate, ellipsoid conidia with obtuse apex and slightly thickened hilum. The sexual morph of the genus is unknown. LSU based phylogeny showed that the X. juglandis clustered with Acrodontium salmoneum (CBS 580.67), and formed a distinct clade sister to Hypocreaceae (Crous et al. 2021). Acrodontium salmoneum has been suggested to belong to Xenoacrodontium, but not formally established. It needs multigene phylogeny to assure the taxonomic placement of Xenoacrodontium. The genus is so far known only as asexual morphs and saprobes.