Tenuitholiascaceae S.H. Jiang, Lücking & J.C. Wei, in Jiang et al., IMA Fungus 11: 1 (2020).
MycoBank number:MB 570578;Index Fungorum number: IF 570578;Fungal Names: FN570578; Facesoffungi number: FoF 08775, 1 species.
Lichenized on leaves chiefly in lowland to montane tropical to subtropical habitats. Thallus supracuticular, easily separated from the leaf surface, smooth, pale green. Photobiont Phycopeltis, cells rectangular, composed of anastomosing filaments in one layer forming regular, radiating plates. Ascomata perithecia, wart-shaped, scattered or somewhat clustered, ostiolate, exposed but covered by thin thallus layer up to the ostiole, with the basal part spreading to form a horizontal plate. Involucrellum carbonized, black. Exciple dense, prosoplectenchymatous, colourless to brown. Hamathecium comprising unbranched paraphyses. Asci bitunicate in structure but lacking a distinct tholus, apex rounded, I–, appearing nearly unitunicate in some stages, clavate to almost cylindrical, I-, KI-, 8-spored. Ascospores irregularly arranged to 2-seriate, fusiform, 3-septate, hyaline. Asexual state: Pycnidia common, wart-shaped, immersed to erumpent, visible as black dots. Conidia acrogenous, only microconidia known; microconidia fusiform, hyaline, aseptate. Chemistry: No secondary substances detected in TLC.
Type: Tenuitholiascus S.H. Jiang, Lücking & J.C. Wei.
Notes: The family was introduced by Jiang et al. (2020a) to accomodate a novel lineage sister to Strigulaceae, but with a different ascus type. To assess placement of the new lineage within Dothideomycetes, a dataset consisting of three loci (SSU, LSU, and tef1-α) was constructed and analysed. Even if superficially similar to Porina in Lecanoromycetes, it was evident that the new lineage was a member of class Dothideomycetes, forming a clade supported sister to Strigulaceae. Since the asci of the novel lineage differed from those of Strigulaceae in lacking a thickened tholus and ocular chamber, it was considered prudent to introduce the monospecific family Tenuitholiascaceae and genus Tenuitholiascus for this taxon. The specific epithet, T. porinoides, thereby refers to the remarkable similarity with Porina both in morphological and anatomical features.