Heterosphaeria Grev., Scott. crypt. fl. 1: pl. 103 (1824)
= Heteropatella Fuckel, Jb. nassau. Ver. Naturk. 27-28: 54 (1874) [1873-74]
Facesoffungi number: FoF 07419
Leotiomycetes, Leotiomycetidae, Helotiales, Heterosphaeriaceae
Saprobic on the host plant in terrestrial habitat. Sexual morph: Apothecia dark brown to black, solitary, sessile, seated on a more or less distinct subiculum of brown, septate hyphae, which penetrate the host tissue, globose to subglobose. Excipulum 2-layered, outer layers crust-like, composed of thin-walled, dark brown, isodiametrical cells of textura globosa to textura angularis, inner layers composed of relatively thick-walled, hyaline, agglutinated, orientated to somewhat interwoven and anastomosing, short, cartilaginous celled-hyphae, gradually merging with thin-walled, hyphae of textura porrecta towards the margin; inside of the apothecial margin with few, free hyphal tips or bordered with regularly arranged, bristle-like hyphae. Paraphyses hyaline, filiform, unbranched, 1–3-septate, apex enlarged club-like, exceeding the asci. Asci cylindrical to clavate, with trapezoidal apex and an apical pore blued by iodine. Ascospores hyaline, irregularly biseriate above, uniseriate at the base, ellipsoidal, often slightly inequilateral, aseptate, or sometimes 1-septate, usually with a large guttule at both ends (Leuchtmann 1987). Asexual morph: Conidiomata black, stromatic, pycnidial, cupulate, sometimes with laciniate margins after dehiscence, solitary to gregarious or confluent, semi-immersed to superficial, unilocular, glabrous, ostiolate or ostiole absent, papillate, thick-walled. Ostiole cylindrical to obconic, single, centrally or excentricity located, sometimes with an operculum. Conidiomatal wall composed of an outer textura angularis to textura globosa, with thick-walled, dark brown to black cells, and an inner textura prismatica, merging with innermost, hyaline, thin layers of hyaline cells of textura angularis near the conidial hymenium. Conidiophores hyaline, subcylindrical, branched, septate, lining the base and most of the way up the side walls of the conidiomata. Conidiogenous cells hyaline, cylindrical, discrete, smooth-walled. Conidiogenesis: ontogeny holoblastic by apical wall-building in the first conidium and replacement wall-building in subsequent conidia; maturation by moderate diffuse wall-building synchronous with conidium ontogeny; delimitation by a transverse septum; secession schizolytic; proliferation of conidiogenous cells holoblastic-sympodial; collarettes, periclinal thickenings, annellations, and regeneration of conidiogenous cells absent (Nag Raj 1993). Conidia hyaline, fusiform, 1–4-septate, slightly constricted at septa, guttulate, smooth, bearing appendages, basal cell obconic with a truncate base, median cells mostly 2–3, sometimes 4, cylindrical to doliiform, apical cell narrow conical and attenuated into an unbranched, cellular appendage, basal appendage attenuated, unbranched, excentric.
Notes: Morphological criteria alone has resulted in a poor understanding in Heterospheria. For example, Rehm (1896) placed Heterospheria in the family Heterosphaeriaceae, Boudier (1907) in Patellariaceae and von Höhnel (1918) in Dermateaceae as it is closely related to Pyrenopeziza Fuckel. Leuchtmann (1987) revised Heterosphaeria and accepted eight species in the genus.
The asexual morph of Heterosphaeria was discovered by Tulasne in 1865 on the same substrate, with asci in apothecia and separate conidiomata (Buddin and Wakefield 1926, Leuchtmann 1987). Grove (1937) linked Heterosphaeria linariae to the asexual morph Heteropatella lacera (type species of Heterosphaeria). However, Leuchtmann (1987) linked H. patella to Heteropatella lacera based on culture studies. Ekanayaka et al. (2019) and Kuntida et al. (2019) showed that Heteropatella lacera was the correct asexual morph of H. linariae based on molecular data.
Distribution: Austria, Czechoslovakia, Germany, Italy, Latvia, Romania, Russia, Sweden, UK, (Nag Raj 1993, Ekanayaka et al. 2019, this study).
Li WJ, McKenZie EHC, Liu JK, Bhat DJ, Dai DQ, Caporesi E, Tian Q, Maharachcikumbura SSN, Luo ZL, Shang QJ, Zhang JF, Tangthirasunun N, Karunarathna SC, Xu JC, Hyde KD (2020) Taxonomy and phylogeny of hyaline-spored coelomycetes. Fungal Diversity 100: pages279–801.