Arthopyrenia A. Massal., Ric. auton. lich. crost. (Verona): 165 (1852).
MycoBank number: MB 325; Index Fungorum number: IF 325; Facesoffungi number: FoF 08162; 53 morphological species (Species Fungorum 2020), 4 species with molecular data.
Type species – Arthopyrenia cerasi (Schrad.) A. Massal.
Notes – Arthopyrenia occur as lichenized, lichenicolous or non-lichenized fungi (Coppins 1988). Both asexual morph and sexual morph have been reported in Wijayawardene et al. (2017a). Taxa in this genus are characterized by dimidiate perithecoid which are scattered to irregularly confluent ascomata, with an upper thick clypeate wall composed of periderm cell intermixed with dark hypae. The fertile locule below the involucrellum is surrounded by thin, sometimes scarcely detectable, hyaline or brown excipulum composed of compacted hypae. The asci are shaped from obpyriform, obclavate to subcylindric, usually 8 spored. The ascospores are oblong, ovoid, slipper- shaped, 1–3 septate, hyaline and smooth with a distinct epispore, and branched anastomosed paraphyses, with a trentepohlia photobiont (Coppins 1988, Upreti & Pant 1993).