Nigrograna pruni P.C. Ding, Y.C. Liao, Y. Jin & Maharachch., 2025

Nigrograna pruni P.C. Ding, Y.C. Liao, Y. Jin & Maharachch. , sp. nov. ( FIGURE 2 View FIGURE 2 )

MycoBank: MB 860248

Etymology: The species epithet refers to the host genus, Prunus , from which the fungus was isolated.

Saprobic on the dead stem of the sweet cherry. Sexual morph: Ascomata 143–210 × 144–255 μm (= 166 × 187 μm, n = 10) scattered or aggregated in small groups, immersed in bark and wood with only ostiolar necks visible on the host surface or immersed erumpent, only rarely becoming superficial, globose to flattened-globose; surrounded by a subiculum of brown to olivaceous, with an ostiole. Ostioles black, cylindrical to papillate-conical, rounded at apex, central, periphysate. Peridium 23–44 μm (= 36.3 μm, n = 20) pseudoparenchymatous, two layers of angular cells, inner wall thinner, paler, outer wall thicker, dark reddish-brown. Asci 41–66 × 5–7 μm (= 50.8 × 6.7 μm, n = 30) 8 spores arranged in the upper part, oblong to clavate, bitunicate, short-stalked, and with a minute ocular chamber. Ascospores 11–18 × 3–5 μm (= 13.6 × 3.9 μm, n = 50), fusiform to ellipsoidal, 3-septate, straight or curved, hyaline to pale yellow when immature, brown to dark brown at maturity, guttulate, constricted at each septum, smooth or faintly verruculose. Asexual morph: Not observed.

Colony characteristics: Conidia germinating on PDA within 8 h at 24 °C. Colonies on PDA reaching 20 mm diameter after 15 days at 25 °C. Mycelia circular, slightly raised, smooth in surface, white; reverse, dark brown center with light brown edges.

Materials examined: CHINA, Sichuan Province, Chengdu City, Dujiangyan County, Yunhua Mountain, on a dead stem of the sweet cherry, 31˚00'74''N, 104˚56'19''E, 1535 m, 22 March 2024, Y. Jin YHS14_1(HKAS 150024, holotype), ex-type UESTCC 25.0261 = CGMCC.

Notes: Multi-gene phylogeny revealed that Nigrograna pruni forms a sister clade to N. norvegica (CBS 141485), with (92/ 1.00) statistical support ( FIGURE 1 View FIGURE 1 ). The BLASTn analysis of N. pruni and N. norvegica (CBS 141485) shows 98% identity (422/431 bp, 1 gap) in ITS, 100% identity (533/533 bp, no gaps) in SSU, and 93% identity (739/685 bp, no gaps) in RPB 2. Species of the Nigrograna are similar in morphology with overlapping characteristics, making it difficult to delimit species based solely on morphological features ( Jaklitsch and Voglmayr 2016; Zhang et al. 2020). Morphologically, N. pruni conforms to the characteristics of the genus Nigrograna : having immersed globose to subglobose ascomata, cylindrical to clavate and apedicellate asci, as well as fusoid to narrowly ellipsoid 3- septate mature ascospores. Therefore, based on combined phylogenetic and morphological evidence, we describe our collection here as a new species, Nigrograna pruni .