Sclerotiophoma L.W. Hou, L. Cai & Crous, in Hou, Groenewald, Pfenning, Yarden, Crous & Cai, Stud. Mycol. 96: 350 (2020)

Index Fungorum number: IF 833512; MycoBank number: MB 833512; Facesoffungi number: FoF 11531

Etymology – Name refers to the producing of pycnosclerotia.

Asexual morph: Conidiomata pycnidial, globose, subglobose, scattered, solitary or confluent, semi-immersed or immersed in agar, without distinct ostioles, occasionally with a pore; pycnidial wall pseudoparenchymatous, multi-layered, outer layers slightly pigmented. Pycnosclerotia present. Conidiogenous cells phialidic, hyaline, smooth, ampulliform or bottle-shaped, with minute periclinal thickening. Conidia ellipsoidal to ovoid, smooth- and thin-walled, aseptate, with or without several guttules. Chlamydospores not observed. Sexual morph unknown.

Type species – Sclerotiophoma versabilis (Boerema et al.) L.W. Hou, L. Cai & Crous

Notes – According to Boerema et al. (2004), most species of Phoma section Sclerophomella have thick-walled pseudoparenchymatous pycnidia in vivo. The type species Phoma complanata of this section has been recombined into Calophoma, and most other species have also been transferred to different genera based on the current phylogenetic analysis, such as Phoma dictamnicola to Heterophoma, and Phoma polemonii to Neodidymelliopsis (Chen et al. 2015). Among the species included in Phoma section Sclerophomella, Phoma versabilis is characterised by the production of pycnidia showing a retarded development of the pycnidial cavity (pycnosclerotia), containing a compact mass of cells that afterwards disintegrates (Boerema et al. 2004). In the present study, phylogenetic analysis showed that this species formed a separate lineage distant from all known genera in Didymellaceae. Therefore, a new genus, Sclerotiophoma, is introduced.