Trypethelium Spreng., Anleit. Kennt. Gew. 3: 350 (1804).
MycoBank number: MB 5628; Index Fungorum number: IF 5628; Facesoffungi number: FoF 08785; 16 morphologically defined species (Aptroot and Lücking 2016; Lücking et al. 2017); molecular data available for six species (Lücking et al. 2016).
Lichenized on bark in terrestrial, lowland to lower montane tropical habitats. Thallus corticate, yellow-brown to olive-green. Photobiont Trentepohlia. Ascomata aggregated in pseudostromata, sessile, brown-black or covered by algal-free, sterile tissue filled with crystalline, yellow to orange, KOH+ red to purple pigment, globose, coriaceous to carbonaceous, ostiolate, ostiole round. Excipulum prosoplectenchymatous, dark brown to brown-black. Hamathecium comprising 0.5–0.7 µm wide paraphysoids, hyaline, straight, branched and anastomosing, embedded in a thick, gelatinous matrix. Asci 8-spored, bitunicate, fissitunicate, obclavate, short pedicellate, with refractive ring and nonamyloid ocular chamber. Ascospores irregularly arranged to biseriate, fusiform, hyaline, multi-septate, with thin distosepta and more or less rectangular lumina, smooth-walled, not constricted at the septa, surrounded by an evanescent mucilaginous sheath. No asexual state known.
Chemistry: Yellow to orange or red anthraquinones and perylenequinones produced in the pseudostromata.
Type species: Trypethelium eluteriae Spreng., Anleit. Kennt. Gew. 3: 350 (1804).
Notes: A tropical, lichenized genus found on bark of branches and trunks of trees, usually in (semi-)exposed situations. Traditionally, Trypethelium included all Trypetheliaceae with thallus-dominated perithecia with separate, apical ostioles and transversely septate, astrothelioid ascospores. In its current circumscription, the genus is limited to species with pseudostromatic perithecia, the pseudostromata typically containing yellow to orange, crystalline pigments, and multi-septate ascospores with more or less thin septa and walls and rectangular lumina (Aptroot and Lücking 2016).