Biatriospora K.D. Hyde & Borse, Mycotaxon 26: 263 (1986).

MycoBank number: MB 25748; Index Fungorum number: IF 25748; Facesoffungi number: FoF 08167; 1 morphological species (Species Fungorum 2020), 1 species with molecular data.

Type species – Biatriospora marina K.D. Hyde & Borse.

Notes – Biatriospora is a monotypic genus and it is morphologically distinct from other genera in the Pleosporales in having ascospores with conical end chambers similar in appearance to those in species of Lulworthia and some species of Spathulospora (Kohlmeyer & Kohlmeyer 1979). However, these genera differ in ascal morphology, bitunicate in Biatriospora, while unitunicate in Lulworthia and Spathulospora, and in the release of mucilage from the end chambers (Jones 1994, 1995). Biatriospora marina, the type species of the genus was originally collected and described from mangrove roots of Sonneratia alba from Anse Boileau mangrove stand, Seychelles (Hyde & Borse 1986). Multi-gene phylogenetic analysis indicated that B. marina formed a separate clade, sister to other families of Pleosporales (Suetrong et al. 2009). Ahmed et al. (2014b) combined asexual species, Nigrospora mackinnoii, which is the causal agent of eumycetoma, with Biatriospora based on combined datasets of LSU, rpb-2, SSU, tef1 employing Bayesian analysis and maximum likelihood phylogeny (for morphology see Zhang et al. 2012b).

Jaklitsch & Voglmayr (2016) introduced Nigrogranaceae to accommodate Nigrograna species and suggested to terminate the use of Biatriosporaceae, since sequence data are doubtful. Biatrisopora now contains only one species as other species were synonymized under Nigrograna (Kolařík 2018). Biatriospora marina along with the present new species Biatriospora borsei clustered separately from species of Nigrograna excepting N. fiscidula. Nigrograna fiscidula was originally known as Melanomma fiscidula but based on molecular sequence differences it was transferred to Nigrograna. While species belonging to Nigrograna produce pycnidial asexual morphs, our new taxon B. borsei produced a hyphomycetous asexual morph in culture and clades closely with B. marina in the phylogram. Though a pycnidial asexual morph connection has been indicated for N. fiscidula it was from natural substrate and not from a culture (Jaklitsch & Voglmayr 2016). An isolate of Biatrispora marina labelled as CY 1228 used in the present study in phylogenetic analysis was excluded by Jaklitsch & Voglmayr (2016) in their tree as it clustered separately and also due to the unique morphological features when compared to species belonging to Nigrograna. Jaklitsch & Voglmayr (2016) suspected whether this isolate indeed represents B. marina and mentioned the necessity to get fresh collections and molecular anlaysis of this fungus. Considering these observations, we consider that synonymizing Biatriosporaceae with Nigrogranaceae is not justified. Further, since both Biatriospora and Nigrograna clade closely, Biatriosporaceae may be retained for these two genera based on the chronological priority of the family names.

Species