Nigrograna Gruyter, Verkley & Crous, Stud. Mycol. 75: 31 (2012).
Saprobic or pathogenic on host. Sexual morph: Ascomata depressed globose to globose, immersed in wood and bark, erumpent, less commonly superficial, scattered or aggregated in small groups, black, seated on or surrounded by olivaceous or brown, KOH-negative subiculum. Ostiolar necks papillate to cylindrical; ostioles periphysate. Peridium pseudoparenchymatous, cells thin-walled and lighter at the inner side, thick-walled and darker at the outer side, usually covered by hyphae. Hamathecium consisting of apically free paraphyses originating in the subhymenium between developing asci, later becoming elongated, branching and anastomosing and appearing as “trabeculate pseudoparaphyses”. Asci clavate, bitunicate, fissitunicate, with short stipe and knob-like base, containing 8 ascospores biseriately arranged in the upper part. Ascospores asymmetric, fusoid to narrowly ellipsoid with the second cell slightly wider than others, straight or curved, 1–3- euseptate, pale to chocolate brown, smooth or faintly verruculose (Adapted from Jaklitsch & Voglmayr, 2016). Asexual morph: Pycnidia solitary or rarely confluent, on upper surface or submerged in agar, globose to subglobose or pyriform, with dark brown, septate mycelial outgrowths, with papillate ostioles, olivaceous to olivaceous-black, the wall with pseudoparenchymatous cells. Conidiogenous cells hyaline, phialidic, discrete. Conidia sub-hyaline, brown in mass, aseptate, ellipsoidal (Adapted from de Gruyter et al., 2013).
Type species: Nigrograna mackinnonii (Borelli) Gruyter, Verkley & Crous
Notes: Nigrograna was introduced by De Gruyter et al. (2013) with N. mackinnonii as type species. Nigrograna is characterized by depressed globose to globose ascomata, papillate to cylindrical ostiolar necks, clavate, bitunicate, fissitunicate asci with short stipe and knob-like base and fusoid to narrowly ellipsoid 1–3- euseptate, pale to chocolate brown ascospores. Nigrograna mackinnonii was previously known as Pyrenochaeta mackinnonii but was not congeneric with the type of Pyrenochaeta, P. nobilis. Nigrograna resembles members of Teichospora in having apically free paraphyses among immature asci but both genera are phylogenetically distinct. Jaklitsch and Voglmayr (2016) described the sexual morph and asexual morph from natural substrates by introducing three species Nigrograna mycophile, N. norvegica and N. obliqua from Austria and Norway. The authors also synonymized Melanomma fuscidulum (≡ Sphaeria fuscidula) as Nigrograna fuscidula. Hyde et al. (2017) and Tibpromma et al. (2017) added Nigrograna thymi from Italy and N. cangshanensis from China respectively. Several authors added new species to Nigrograna (Kolařík, 2018; Zhao et al., 2018; Dayarathne et al., 2020). Nigrograna is morphologically and phylogenetically a well-defined genus in Nigrogranaceae.