Buelliella Fink, Lich. Fl. U.S.: 372 (1935).
MycoBank number: MB 676; Index Fungorum number: IF 676; Facesoffungi number: FoF 03625; 12 morphological species (Species Fungorum 2020, this study), 2 species with molecular data.
Type species: Buelliella minimula (Tuck.) Fink, Lich. Fl. U.S.: 372 (1935).
≡ Buellia minimula Tuck., Syn. N. Amer. Lich. (Boston) 2: 106 (1888).
Notes: The original diagnosis of this genus was provided by Fink (1935), and valided by Hafellner (1979). Buelliella is characterised by a non-lichenized, lichenicolous habit, initially subsphaerical and closed ascomata, with the upper ascomatal breaking gradually away to expose the hymenium when mature, becoming apothecioid, with bitunicate, broadly clavate to subcylindrical asci, and a distinct ocular chamber, and ellipsoid, 1-septate, pale to medium brown ascospores. Ertz and Diederich (2015) noted that the genus is not monophyletic due to B. physciicola and B. poetschii being distantly related, and sequence data of the type species (B. minimula) was unavailable. Thus, it was placed as incertae sedis in Dothideomycetes (Kirk et al. 2008; Ertz and Diederich 2015; Wijayawardene et al. 2017a). We included sequence data of B. minimula in our analyses and found that it forms a lineage within Sticgraphaceae. Buelliella poetschii is transferred to a new genus, Neobuelliella in this paper.