Xenoconiothyrium Crous & Marinc., in Crous, Summerell, Swart, Denman, Taylor, Bezuidenhout, Palm-Hernández, Marincowitz & Groenewald, Persoonia 27: 42 (2011)
Index Fungorum number: IF 560572; Facesoffungi number: FoF 01731, 1 morphological species (Species Fungorum 2021), 1 species with molecular data.
Endophytic or saprobic on twig. Sexual morph: Unknown. Asexual morph: Mycelium consisting of septate, branched, olivaceous-brown to brown, thick-walled, warty hyphae, covered in a mucoid layer, giving rise to pycnidial conidiomata. Conidiophores reduced to phialidic conidiogenous cells that line the cavity, ampulliform, hyaline, tapering to an abrupt apex. Conidia initially in short chains 3(–4), attached via a small locus, eventually breaking free, with minute loci visible on conidial ends, ellipsoid to sub cylindrical, thick-walled, initially hyaline, smooth, becoming verruculose, dark brown, 0(–1)-septate, not or constricted at septum, apex obtuse, widest at septum, tapering abruptly to truncate hilum (when viewed directly from above, it appears to have a central pore, which can be basal, or present at both conidial ends); not thickened nor darkened. Spermatia at times formed in same conidioma, hyaline, bacilliform (Adapted from Crous et al. 2011).
Type species: Xenoconiothyrium catenatum Crous, Summerell, Swart, Denman, Taylor, Bezuidenhout, Palm-Hernández, Marincowitz & Groenewald
Notes: Xenoconiothyrium was introduced by Crous et al. (2011) with X. catenatum as type species. Xenocamarosporium resembles Pseudohendersonia but is unique in having conidia with an obtuse apex truncate to rounded base. Xenoconiothyrium differs from Coniothyrium sensu stricto in having immature conidia which form in chains and pores visible at one or either end. Phylogenetically, Xenoconiothyrium is a well-supported genus in Teratosphaeriaceae.