Nigrograna aquatica W. Dong, H. Zhang & K.D. Hyde
Index Fungorum number: IF557907; Facesoffungi number: FoF09250
Etymology: in reference to aquatic habitat of this fungus
Holotype: MFLU 17-1661
Saprobic on submerged wood in freshwater. Sexual morph: Undetermined. Asexual morph: Synnemata 110–125 × 8.5–14.5 μm ( = 118 × 11.8 μm, n = 5), superficial, effuse, gregarious, black, upper part covered with a white or pale grey powdery mass of conidia, composed of paralleled conidiophores. Mycelium mostly immersed, composed of septate, pale brown, smooth hyphae. Conidiophores 100–120 × 1.5–2 μm ( = 100.5 × 1.7 μm, n = 15), macronematous, synnematous on substratum, not compacted, become divergent after mounted in water, unbranched, septate, not constricted at the septa, smooth, dark brown at the base, gradually paler towards the apex, flared in upper part. Conidiogenous cells 4–7.5 × 1.7–2.5 μm ( = 5.6 × 2.2 μm, n = 10), polyblastic, terminal or intercalary, integrated when terminal and discrete when intercalary, sympodial, smooth, swollen subcylindrical, flask-shaped, ampulliform, curved or straight, denticulate, covered with several conidiogenous loci at the upper part, hyaline to subhyaline. Conidia 6–7 × 2–2.5 μm ( = 6.6 × 2.2 μm, n = 15), solitary, acrogenous, simple, dry, ellipsoidal or cylindrical, smooth, thin-walled, aseptate, hyaline. (Descriptions from Dong et al. 2020)
Culture characteristics: On PDA, colony circular, reaching 25 mm diam. in 30 days at 25 °C, brown to grey from above, dark brown from below, surface rough, with dense mycelium, dry, raised, edge entire.
Material examined: THAILAND, Phayao Province, on submerged wood in a stream, 4 August 2017, G.N. Wang, G11 (MFLU 17-1661, holotype), ex-type living culture MFLUCC 17-2318.
Notes: Nigrograna aquatica is morphologically similar to Phaeoisaria species which are characterized by synnematous conidiophores with polyblastic, sympodial conidiogenous cells (Cai et al. 2006). However, they cannot be congeneric because N. aquatica differs in having not compacted synnemata which easily become divergent after mounted in water. In contrast, the conidiophores of Phaeoisaria are compacted and parallel adpressed, and never become divergent in water (Liu et al. 2015; Hyde et al. 2018; Luo et al. 2018). The ellipsoidal or cylindrical, hyaline, aseptate, small conidia of N. aquatica are similar to those coelomycetous species in Nigrograna (de Gruyter et al. 2013; Jaklitsch and Voglmayr 2016). However, phylogenetic analyses showed them as distinct species. The phylogenetically closest species N. locutapollinis F. Liu & L. Cai was isolated from hive-stored pollen collected in Italian honeybee colonies, while N. aquatica was collected from submerged wood in freshwater habitats in Thailand. Morphology of N. locutapollinis was not given in protologue (Zhao et al. 2018). A comparison of their nucleotides shows that there are six and eight (including two gaps) nucleotide differences in LSU and ITS sequence data, respectively. Dong et al. (2020) introduce N. aquatica based on morpho-phylogenetic analysis and this is the first hyphomycetous species in Nigrograna. (Notes from Dong et al. 2020).
Freshwater distribution: Thailand (Dong et al. 2020)