Pyrenidiaceae Zahlbr. in Engler, syllabus der Pflanzenfamilien, Edn 2 (Berlin): 46 (1898).

MycoBank number: MB 81790; Index Fungorum number: IF 81790; Facesoffungi number: FoF 07908, 13 species.

Lichenicolous on various substrates such as bark, rock, soil, bryophytes or living leaves. Sexual morph: Ascomata perithecioid, densely grouped or dispersed over large areas of the thallus, sessile or immersed in the host thallus, black, in longitudinal section, subglobose to broadly ovoid or pyriform, often with light greenish-blue tint in the ostiolar canal. Peridium with isodiametric to elongated cells, brown to dark brown. Hymenium hyaline, I-, KI-. Hamathecium of numerous, persistent, branched, anastomosing pseudoparaphyses; apical cells not enlarged; non-branching periphyses. Asci 4–8-spored, bitunicate, short pedicellate, I-, KI-, ocular chamber not distinct. Ascospores 1–2-seriate, oblong to ellipsoidal, or fusiform, dark brown, often paler brown at the spore tips, 3-septate, smooth-walled. Asexual morph: Undetermined (adapted from Huanraluek et al. 2019a).

Type: Pyrenidium Nyl.

Notes: Huanraluek et al. (2019a) provided sequence data for Pyrenidium species and indicated that Pyrenidium formed a distinct clade outside Dacampiaceae. However, Huanraluek et al. (2019a) did not assign Pyrenidiaceae to any order. Pyrenidiaceae formed a distinct clade outside Pleosporales in personal analyses of Hongsanan et al. (2020, data not showed), and formed within Pleosporales as a distinct family (data not showed) in the dataset which includes all representative families in Dothideomycetes (data not showed). Therefore, we agree with Huanraluek et al. (2019a) to treat this family as incertae sedis in Dothideomycetes until more collections with multi-loci are available to clarify its phylogenetic placement.