Sphaerulina Sacc., Michelia 1: 399 (1878).
Index Fungorum number: IF 5128; Facesoffungi number: FoF 08563, 71 morphological species (Species Fungorum 2022), 31 species with molecular data.
Pathogenic on host. Sexual morph: Ascomata pseudothecial, immersed, subepidermal, erumpent at the apex, single to clustered, globose, papillate. Ostiole central, with hyaline periphyses; wall of textura angularis, composed of 2–4 layers of brown cells. Hamathecium dissolving at maturity. Asci bitunicate, fissitunicate, clustered, cylindrical to obclavate, rounded at apex, with or without a shallow apical chamber, short stipitate or sessile, with 8 bi- to triseriate ascospores. Ascospores subcylindrical to fusiform, rounded at ends, slightly tapered, straight or slightly curved, 1–3-septate, with a primary septum nearly median, hyaline, smooth, without sheath or appendages. Asexual morph: Unknown (adapted from Videira et al. 2017).
Type species: Sphaerulina myriadea (DC.) Sacc.
Notes: Sphaerulina is characterised by subepidermal, globose, papillate ascomata, cylindrical to obclavate asci and subcylindrical to fusiform, 3-septate ascospores. Sphaerulina differs from Mycosphaerella based on ascospore septation (Crous et al. 2003, 2011). Crous et al. (2011) mentioned that strains of Sphaerulina myriadea were species complexes and abstained from designating an epitype based on an authentic specimen collected on Quercus from France. In the phylogenetic analyses of Quaedvlieg et al. (2013) and Verkley et al. (2013), Sphaerulina was closely related to Septoria. Videira et al. (2017) found that Sphaerulina and Miuraea clustered together and phylogeny was not able to separate these two genera. Sphaerulina is currently a distinct but paraphyletic genus in Mycosphaerellaceae and more taxa need to be sequenced to verify the status of the genus. Molecular markers available for Sphaerulina are ITS, LSU, SSU, Actin, BTUB, Calmodulin, Histone, RPB2 and TEF-1.