Exosporium Link, Mag. Gesell. naturf. Freunde, Berlin 3(1–2): 9 (1809).
MycoBank number: MB 8240; Index Fungorum number: IF 8240; Facesoffungi number: FoF 08499; 42 morphological species (Species Fungorum 2020), 3 species with molecular data.
Type species – Exosporium tiliae Link, Mag. Gesell. naturf. Freunde, Berlin 3(1-2): 10 (1809).
Notes – Exosporium was introduced by Link (1809) with E. tiliae as the generic type. Exosporium, once considered a synonym of Helminthosporium due to morphology or phylogeny, exemplifies polyphyletic within the group (Fries 1832, Voglmayr & Jaklitsch 2017). Exosporium species are dematiaceous hyphomycetes with diverse lifestyles, including phytopathogenic, saprobic, and endophytic modes, and they exhibit a wide distribution (Zhao & Zhao 2012, Singh et al. 2015, Videira et al. 2017). There are about 42 recognized species in this genus, but additional evidence is required to clarify the status of related species, with molecular data lacking for many of them (Singh et al. 2015, Videira et al. 2017). Exosporium members are characterized by macronematous, mononematous, often caespitose, unbranched or branched, mid to dark brown or olivaceous brown, smooth or verruculose conidiophores, polytretic, integrated, terminal, becoming intercalary, sympodial, cylindrical or clavate, cicatrized conidiogenous cells, usually solitary, short catenate, acropleurogenous, simple conidia, with mostly obclavate, pale to dark brown or olivaceous brown, smooth, verrucose or echinulate, distoseptate, generally with a thick, dark hilum at the base (Ellis 1961, Videira et al. 2017).
Species