The genus <i>Hermatomyces</i> in Benin, with the description of <i>H. griseomarginatus</i>, sp. nov.

Intensive mycological surveys in southern Benin focused on species of <i>Hermatomyces</i> (Pleosporales) resulted in the collection and sequencing of numerous specimens on dead plant debris of different hosts. Majority of the collections belonged to the monomorphic species <i>H. sphaericus</i>, except for two specimens of a hitherto unknown species, which is introduced as <i>Hermatomyces griseomarginatus</i>. The fungus was collected on dead twig of <i>Hymenocardia acida</i> still attached to the tree and dead peduncle of <i>Tectona grandis</i>. It is distinct in having sporodochia with a dense and dark gray margin enclosing their lenticular conidia. Phylogenetically, it formed a well-supported lineage sister to two other monomorphic species, <i>H. verrucosus</i> and <i>H. sphaericoides</i>. Two dimorphic species were also found, <i>H. krabiensis</i> and <i>H. nabanheensis</i>, which are reported for the first time outside of Asia. Detailed morphological descriptions are provided, and the diversity of <i>Hermatomyces</i> in Benin is summarized based on published data and results from the GlobalFungi database.