Nigrograna lancangensis

Nigrograna lancangensis G.C. Ren & K.D. Hyde, in Ren, Jayasiri, Tibpromma, Farias, Chethana, Faraj, Wanasinghe, Xu, Hyde & Gui, Mycosphere 15(1): 1030 (2024)

Index Fungorum number: IF901354; FacesofFungi number: FoF13886

Saprobic on dead twigs of Castanopsis mekongensis. Sexual morph: Ascomata 140–306 μm high, 189–509 μm diam., (x̅ = 196 × 323 μm, n = 5), immersed to erumpent, solitary or scattered, elliptical to ampulliform, dark brown, 1–2-loculate. Ostioles 110–170 × 62–103 (x̅ = 141 × 81, n = 5) μm, black, papillate, central. Peridium 12–20 μm wide, 3–4-layered, composed of dark brown cells of textura angularis. Hamathecium 1.4–2.5 μm wide, comprising numerous, filamentous, branching, septate, cellular pseudoparaphyses. Asci 75–95 × 13–15 μm (x̅ = 79 × 14 μm, n = 20), 4–8-spored, bitunicate, fissitunicate, clavate to cylindric-clavate, slightly curved, short pedicellate, apically rounded. Ascospores 16–21 × 5.5–7.5 μm (x̅ = 17.4 × 6.5 μm, n = 40), overlapping 1–2-seriate, ellipsoid, straight, initially hyaline to yellowish brown, 0–1-septate, becoming dark brown, 3-septate when mature, smooth-walled, with large guttules when mature, in most cases, the upper cell is slightly wider than the lower cell, rounded at both ends, slightly constricted at the primary median septum. Asexual morph: Undetermined.

Culture characteristics: Ascospores germinating on PDA within 24 h at room temperature (25 °C). Germ tubes produced from the first and second cell of ascospore from the apex. Colonies on PDA, reaching 30 mm diameter after two weeks at 20–25 ℃, mycelia superficial, dense, filamentous, flat, slightly raised at the center, surface smooth with fimbriate edge, velvety, dark gray; reverse gray at margin, dark brown at center.

Material examined: China, Yunnan Province, Lancang, Lahu Autonomous Prefecture, Hani, on dead woody twigs of Castanopsis mekongensis (Fagaceae), 20 July 2020, G.C. Ren, LGY18 (HKAS 122735, holotype), ex-type living culture KUMCC 21-0555, KUMCC 21-0556.

GenBank numbers: KUMCC 21-0555: SSU: OQ168220, LSU: OQ170867, ITS: OQ158945, tef1-α: OR613437, rpb2: OR578560; KUMCC 21-0556: SSU: OQ168221, LSU: OQ170868, ITS: OQ158946.

Notes: In the phylogenetic analyses, Nigrograna lancangensis formed a clade sister to N. thymi (MFLUCC 14-1096, KUMCC 21-0548) with 91% ML bootstrap support and 1.00 BYPP value. Nigrograna lancangensis fits well with the generic concept of Nigrograna in having immersed to erumpent ascomata with ostiolar, clavate and fissitunicate asci, ellipsoid, straight, septate, and smooth or verruculose ascospores, but distinct from N. thymi in having bilocular ascomata, ellipsoid, 3-septate ascospores, while N. thymi is characterised by broadly fusiform to inequilateral, 4–5-septate ascospores (Hyde et al. 2017). Sequence comparison for the ITS region between Nigrograna lancangensis (KUMCC 21-0555) and N. thymi (MFLUCC 14-1096) showed a 1.5% (7/484 bp, without gaps) base pair difference in ITS region, 3.7% (34/929 bp, without gaps) base pair difference in the tef1-α region, 0.8% (7/881 bp, without gaps) base pair difference in LSU region. Therefore, Nigrograna lancangensis is introduced as a new species based on its distinct morphology and phylogenetic position.

Figure 1. Phylogram generated from ML analysis based on SSU, LSU, ITS, tef1-α, and rpb2 sequence data, representing Nigrograna (Nigrogranaceae). Related sequences are obtained following de Lu et al. (2022b) and Boonmee et al. (2021). Forty-six strains are included in the combined analyses, which comprise 4194 characters for SSU, LSU, ITS, tef1-α, and rpb2 alignment. Seriascoma didymospora (MFLUCC 11-0194, MFLUCC 11-0179) were used as the outgroup taxa. The best-scoring RAxML tree with a final likelihood value of -17623.075885 is presented. The matrix had 1076 distinct alignment patterns, with 31.53% of undetermined characters or gaps. Estimated base frequencies were as follows; A = 0.248028, C = 0.248350, G = 0.266441, T = 0.237180; substitution rates AC = 1.506227, AG = 4.589175, AT = 1.553542, CG = 1.033267, CT = 10.958332, GT = 1.0000. The tree topology of the ML analysis is similar to the Bayesian analysis. Bootstrap values for ML equal to or greater than 70% and BYPP values greater than 0.95 (the rounding of values to 2 decimal proportions) are labelled on the nodes. Strains of the newly described species are in blue, while type strains are in bold.