Byssosphaeria Cooke, Grevillea 7(no. 43): 84 (1879).
Index Fungorum number: IF 711; Facesoffungi number: FoF 00765, 16 morphological species (Species Fungorum, 2022), 9 species with molecular data.
Saprobic on woody angiosperms. Sexual morph: Ascomata solitary, scattered or sometimes gregarious, globose, subglobose or ovoid, spreading on substrate as a subiculum, coriaceous, ostiolate, wall black, roughened. Ostiole single, flattened, yellow, red or orange coloered at pore. Peridium 2-layered, with outer layer composed of irregular, thick-walled, brown to dark brown cells of textura epidermoidea, with inner layer composed of small thin-walled light brown cells. Hamathecium thick with long, trabeculate pseudoparaphyses, embedded in mucilage, anastomosing between and above asci. Asci 8-spored, bitunicate, fissitunicate, thick-walled, cylindrical to clavate, with short pedicel, apically rounded with an ocular chamber. Ascospores uni-seriate or bi-seriate, pale brown, fusiform, tapering at both ends, mostly straight, sometimes slightly curved, 1-septate, slightly constricted at the septum, minutely verrucose. Asexual morph: Pycnidia formed in culture. Conidiogenous cells phialidic, lining cavity. Conidia hyaline, ellipsoid or subglobose (Adapted from Barr, 1984; Tian et al., 2015).
Type species: Byssosphaeria keithii (Berk. & Broome) Cooke
Notes: Byssosphaeria was introduced by Cooke and Plowright (1879) with B. keithii as type species based on morphology especially the superficial ascomata seated on a “tomentose subiculum of interwoven threads”. Byssosphaeria is characterized by solitary, scattered or sometimes gregarious, globose, subglobose ascomata, cylindrical to clavate, short pedicellate asci and uni-seriate or bi-seriate, pale brown, fusiform ascospores. The asexual morph is characterized by phialidic conidiogenous cells and hyaline, ellipsoid or subglobose conidia. Byssosphaeria keithii was previously considered as a synonym of B. schiedermayeriana (Sivanesan, 1971). von Arx and Müller (1975), Bose (1961), Luttrell (1973), Müller and von Arx (1962) and Sivanesan (1971) synonymized B. schiedermayeriana as Herpotrichia schiedermayeriana. Barr (1984) reported that B. schiedermayeriana is found in tropical or greenhouse environments and excluded H. schiedermayeriana from Herpotrichia and re-surrected Byssosphaeria in Melanommataceae. Barr (1990) provided a detailed description of Byssosphaeria. Zhang et al. (2012) observed that the holotype material of Byssosphaeria schiedermayriana from K(M):108784 and reported that the species has orange, greenish and flat apices. Byssosphaeria differs from Herpotrichia in having trabeculate pseudoparaphyses, and presence of a subiculum (Hyde et al., 2000). Mugambi and Huhndorf (2009), Zhang et al. (2012), Hyde et al. (2013), Tian et al. (2015) confirmed Byssosphaeria as a monophyletic genus in Melanommataceae. Since then, several new species have been introduced in Byssosphaeria (Chen & Hsieh, 2004; Wang et al., 2004; Li & Zhuang, 2008; Liu et al., 2015; Tian et al., 2015; Tennakoon et al., 2018). Byssosphaeria is morphologically and phylogenetically a well-defined genus in Melanommataceae. Molecular markers available for Byssosphaeria include LSU, SSU, ITS, TEF1 and RBP2.