Pyrenophora Fr., Summa veg. Scand., Sectio Post. (Stockholm): 397 (1849)
= Drechslera S. Ito, Proc. Imp. Acad. Japan 6: 355 (1930).
Index Fungorum number: IF 4596; MycoBank number: MB 4596; Facesoffungi number: FoF 000009; 108 species (Species Fungorum 2020), 16 species with molecular data.
Saprobic or pathogenic on leaves and stems. Sexual morph: Ascomata immersed, becoming erumpent to near superficial, solitary or scattered, globose to subglobose, broadly or narrowly conical, smooth-walled, ostiolate. Ostiole papillate, covered with brown to reddish-brown setae, which are darkened at the base. Peridium comprising 2–4 layers of brown thick-walled cells of textura angularis. Pseudoparaphyses not observed. Asci 8-spored, bitunicate, fissitunicate, clavate to sub-cylindrical, with a short, broad pedicel, with a distinct ocular chamber surrounded by a large apical ring. Ascospores 2–3-seriate, muriform, constricted at the septum, smooth-walled, surrounded by a mucilaginous sheath. Asexual morph: hyphomycetous. Conidiophores macronematous, mononematous, sometimes caespitose, straight or flexuous, often geniculate, unbranched or in a few species loosely branched, brown, smooth in most species. Conidiogenous cells polytretic, integrated, terminal, frequently becoming intercalary, sympodial, cylindrical, cicatrized. Conidia solitary, in certain species also sometimes catenate or forming secondary conidiophores which bear conidia, acropleurogenous, simple, straight or curved, clavate, cylindrical, rounded at the ends, ellipsoidal, fusiform or obclavate, straw-coloured or pale to dark brown or olivaceous brown, sometimes with cells unequally coloured, the end cells then being paler than intermediate ones, mostly smooth, rarely verruculose, pseudoseptate (description of asexual morph obtained from
Ellis 1971).
Type species – Pyrenophora phaeocomes (Rebent.) Fr., Summa veg. Scand., Sectio Post. (Stockholm): 397 (1849).
≡ Sphaeria phaeocomes Rebent., Prodr. fl. neomarch. (Berolini): 338 (1804).
Notes – Based on both morphology and molecular data, Pyrenophora has been assigned to Pleosporaceae (Zhang et al. 2012). The genus is characterized by immersed, erumpent to nearly superficial ascomata, asci usually with a large apical ring with a clear ocular chamber, lack of pseudoparaphyses and muriform, terete ascospores (Sivanesan 1984). Currently, 199 species of Pyrenophora are listed in Index Fungorum (2015). Over 3000 hits are found in GenBank including the putative strain of Pyrenophora phaeocomes (DAOM 222769), which is the type species for this genus. In the present study the genus Pyrenophora clusters in the suborder Pleosporineae of the family Pleosporaceae with a relatively high bootstrap support (60 %). Further phylogenetic analysis shows that sexual Pyrenophora morphs cluster with asexual Drechslera morphs, i.e., Pyrenophora dictyoides (DAOM 75616) clusters with Drechslera dictyoides (DAOM 63666). The putative strain of Pyrenophora phaeocomes (DAOM 222769), which is the type species of the genus, clusters with other Pyrenophora species. As a genus can now only have one name, Ariyawansa et al. (2014c) proposed to synonymise Drechslera under Pyrenophora by giving the priority for the oldest name. This was followed by Wijayawardene et al. (2014).