Pyrenochaeta
Pyrenochaeta De Not., Mém. R. Accad. Sci. Torino, Ser. 2 10: 347 (1849).
Index Fungorum number: IF 9667; Facesoffungi number: FoF 11830, 86 morphological species (Species Fungorum 2022), 2 species with molecular data (>10000 unidentified species with molecular data).
Saprobic or pathogenic on host. Sexual morph: Unknown. Asexual morph: Conidiomata immersed becoming erumpent to superficial, brown, globose, with prominent wide central ostiole, surrounded by a crest of brown setae, straight, flexuous, unbranched, septate with obtusely rounded ends. Conidiomatal wall of 3–4 layers of brown textura angularis. Conidiophores reduced to conidiogenous cells. Conidiogenous cells hyaline, smooth, ampulliform, lining the inner cavity, with prominent periclinal thickening. Conidia solitary, hyaline, smooth, thin-walled, guttulate, subcylindrical with obtuse ends, straight to slightly curved, allantoid (adapted from description of P. pinicola in Crous et al. 2014).
Type species: Pyrenochaeta nobilis De Not.
Notes: Pyrenochaeta is characterised by elongated, septate, acropleurogenous conidiophores formed in pycnidia usually covered by long setae (Crous et al. 2014). The taxonomy of Pyrenochaeta is very complex and challenging to resolve since all species are morphologically similar. We adapted the generic description of Pyrenochaeta from the latest species P. pinicola described by Crous et al. (2014). The classification of species in Pyrenochaeta has been very confusing due to overlapping characters of conidiogenesis and setose pycnidia with similar genera such as Pleurophoma and Phoma sect. Paraphoma (Grondona et al. 1997, De Gruyter et al. 2009). Two species of Pyrenochaeta have been linked to a teleomorph namely P. parasitica with teleomorph Herpotrichia parasitica and P. berberidis with teleomorph Cucurbitaria berberidis. Schneider (1979) excluded P. berberidis from Pyrenochaeta due to different pycnidial characters and setose pycnidia which seemed not to be constant. De Gruyter et al. (2009) attempted to clarify the systematic position of Pyrenochaeta using DNA sequence data of SSU and LSU regions and introduced Pyrenochaetopsis to accommodate P. leptospora. Pyrenochaeta resembles Pyrenochaetopsis in having setose pycnidia but the latter has Phoma-like conidiogenesis (De Gruyter et al. 2009). Sivanesan (1984) and Farr et al. (1989) reported that Cucurbitaria has Pyrenochaeta asexual states. De Gruyter (2010, 2013) demonstrated that P. nobilis and Pyrenochaetopsis leptospora, the generic types of Pyrenochaeta and Pyrenochaetopsis, belong to Cucurbitariaceae. De Gruyter et al. (2010) transferred Phoma cava to Pyrenochaeta and reported that P. nobilis clusters with C. berberidis (= P. berberidis) in the same clade. In the phylogenetic analysis of Doilom et al. (2013), Pyrenochaeta spp. did not cluster together in a monophyletic clade hence they did not synonymize Pyrenochaeta under Cucurbitaria even though some Pyrenochaeta spp. are linked with Cucurbitaria spp. Molecular data is available for only two known species, P. ligni-putridi (CBS 6094) and P. nobilis (CBS 407.76). Pyrenochaeta is currently placed in Pleosporales, genera incertae sedis. Revision of Pyrenochaeta species must be carried out to elucidate a more stable classification of this genus. Pyrenochaeta might comprise many more monophyletic genera with distinct teleomorphic affinities. Molecular markers available for P. ligni-putridi are ITS, LSU and for P. nobilis are ITS, LSU, SSU, Actin, BTUB, RPB2 and TEF-1.
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