Phloeospora Wallr., Fl. crypt. Germ. (Norimbergae) 2: 176 (1833).
Index Fungorum number: IF 9351; Facesoffungi number: FoF 08543, 30 morphological species (Species Fungorum 2022), 1 species with molecular data.
Associated with leaf spot. Sexual morph: Unknown. Asexual morph: Mycelium immersed, septate, hyaline. Conidiomata acervular, subepidermal, circular, discrete or confluent, composed of hyaline to pale brown, thin-walled textura angularis; dehiscence irregular. Conidiophores reduced to conidiogenous cells or with one or two supporting cells, branched at base or not. Conidiogenous cells holoblastic, annellidic, occasionally also sympodial, discrete, indeterminate hyaline, smooth, cylindrical, with several apical inconspicuous annellations, formed from the upper cells of the acervuli. Conidia solitary, hyaline, septate, smooth, guttulate or not, cylindrical, curved, attenuated towards the apices, apex obtuse to subobtuse, base truncate, with minute marginal frill (adapted from Videira et al. 2017).
Type species: Phloeospora ulmi (Fr.) Wallr.
Notes: Phloeospora is characterised by acervular, subepidermal, circular, discrete or confluent conidiomata, holoblastic, annellidic, seldom also sympodial conidiogenous cells and solitary, hyaline, septate, smooth conidia. Phloeospora differs from Septoria in producing conidia in acervuli, whereas conidiomata in Septoria are pycnidial. In the phylogenetic analysis of Quaedvlieg et al. (2013) and Videira et al. (2017), Phloeospora clustered close to but in a distinct lineage from Septoria s. str. Phloeospora is a heterogenous genus and needs revision (Verkley and Priest 2000; Videira et al. 2017). Phloeospora is currently a distinct genus in Mycosphaerellaceae. Molecular markers available for Phloeospora are ITS, LSU, SSU, Actin, Btub, TEF-1 and RPB2.