Bathelium Ach., Method. Lich.: 111 (1803).
MycoBank number: MB 517; Index Fungorum number: IF 517; Facesoffungi number: FoF 08789; 16 morphologically defined species (Aptroot and Lücking 2016; Lücking et al. 2017); molecular data available for four species (Lücking et al. 2016).
Lichenized on bark in terrestrial, chiefly lowland to lower montane tropical habitats, often in drier situations. Thallus corticate, yellow-brown to olive-green. Photobiont Trente-pohlia. Ascomata solitary to aggregated in distinct pseudostromata, prominent to sessile, brown-black and remaining fully exposed, rarely pruinose, coriaceous to carbonaceous, ostiolate, ostiole apical. Involucrellum reduced. Excipulum brown-black. Hamathecium comprising 0.5–0.7 µm wide paraphysoids, hyaline, straight, branched and anastomosing, embedded in a gelatinous matrix. Asci 1–8-spored, bitunicate, fissitunicate, clavate to oblong, short pedicellate, with a non-amyloid ocular chamber. Ascospores irregularly arranged to biseriate, fusiform-ellipsoid, hyaline, septate to mostly muriform, more or less euseptate, smooth-walled, not or slightly constricted at the septa (often at the middle septum only), surrounded by a gelatinous sheath. Pycnidia unknown.
Chemistry: lichexanthone sometimes produced on thallus surface; yellow to orange anthraquinones often produced in the medulla of the pseudostromata.
Type species: Bathelium mastoideum Afz. ex Ach., Method. Lich.: 111 (1803).
Notes: For key and discussion see Aptroot and Lücking (2016).