2.5.2 Biatriospora borsei

Biatriospora, typified by B. marina, was described as a sexual genus from mangrove roots in Seychelles with fusiform, 1 – 4 septate, brown to dark brown ascospores with hyaline polar chambers which release mucilage (Hyde and Borse 1986). Sequences of B. marina from a collection made in Singapore placed this species basal to Lophiostomataceae, Sporormiaceae and a group of unclassified taxa in a phylogenetic analysis of 18 S, 28 S rDNA, RPB 2 and TEF- 1α (Suetrong et al. 2009).

The genus Nigrograna was established to accommodate N. mackinnonii, a species originally described in Pyrenochaeta (de Gruyter et al. 2013) . Hyde et al. (2013) established a new family Biatriosporaceae to accommodate Biatriospora . In a phylogenetic analysis using the same genes, Ahmed et al. (2014) found that N. mackinnonii grouped with B. marina, and thus referred the former species to Biatriospora . Later, four more species of Biatriospora were described from woody plants as endophytes: B. antibiotica, B. carollii, B. yasuniana and B. peruviensis (KolařÍk et al. 2017), unaware that a new family Nigrogranaceae was established to accommodate Nigrograna with N. mackinnonii as the type, and the new combination of Melanomma fuscidulum in Nigrograna and the description of the new species N. mycophila, N. norvegica and N. obliqua (Jaklitsch and Voglmayr 2016) . Jaklitsch and Voglmayr (2016) voiced doubts on the identification of the Biatriospora marina isolate and the validity of the Biatriosporaceae . Consequently, KolařÍk (2018) accepted the genus Nigrograna and the family Nigrogranaceae, and transferred B. antibiotica, B. carollii, B. yasuniana and B. peruviensis to Nigrograna . After these revisions, Biatriospora became a monotypic genus but B. borsei was described as a new species in Hongsanan et al. (2020a). Biatriospora borsei clustered with B. marina (with a good support) within a group of Nigrograna spp. based on 18 S, 28 S, ITS rDNA, RPB 2 and TEF- 1α, although B. borsei is a hyphomycete with no known sexual stage. As discussed here, fresh isolates of B. marina should be collected to clarify the taxonomic position of this species, B. borsei, the genus Nigrograna and the families Biatriosporaceae and Nigrogranaceae .