Homostegia Fuckel, Jb. nassau. Ver. Naturk. 23-24: 223 (1870) [1869-70]
MycoBank number: MB 2359; Index Fungorum number: IF 2359; Facesoffungi number: FoF 09061;
Lichenicolous on thallus of Lichens. Sexual morph: Ascomata immersed to semi-immersed, black, solitary, scattered, or in small groups, discoid to rounded, carbonaceous, multilocular, wall black to grayish, roughened, dehiscence via irregular slit appearing on upper part of the wall. Locules globose to subglobose, forming a single layer within ascostromata. Peridium 1–2 layered, composed of highly pigmented cells of textura angularis, reddish-brown cells. Hamathecium dense with cellular hyaline, septate pseudoparaphyses. Asci 8-spored, bitunicate, fissitunicate, dehiscence not observed, obovoid to broadly cylindrical, forms short, broad, hamate shaped pedicel. Ascospores partially overlapping, fusiform to ellipsoidal to broadly ellipsoidal, brown to reddish- brown, 3-longitudinal septa, constricted at septa, slightly curved, smooth-walled. Asexual morph: Undetermined.
Type species – Homostegia adusta Fuckel
Notes – The genus Homostegia was introduced by Fuckel (1870). Homostegia adusta was isolated from the lichen Parmelia saxatilis in Germany. The genus is characterized by black multiloculate stromata and brown 3-septate and regularly asymmetric ascospores. Currently, the genus Homostegia comprises five species. The asexual morph is unknown. No cultures or molecular data are available. Doilom et al. (2018) studied the lectotype specimen, Homostegia piggotii and mentioned that the latter is the synonym of Homostegia adusta and retained the genus in Pleosporales, genera incertae sedis. In this study, we re-examined the holotype specimen of Homostegia adusta under the code G-322312/1 from G herbarium. Both Homostegia piggotii and Homostegia adusta are isolated from the same host namely Parmelia spp. and are characterized by multiloculate ascomata, 8-spored asci as well as dark brown, ellipsoidal to fusiform ascospores. These characters resemble species of the family Decampiaceae. However, we retain the genus in Pleosporales, genera incertae sedis until molecular data becomes available.