Nigrograna schimae
Nigrograna schimae G.C. Ren & K.D. Hyde, in Ren, Jayasiri, Tibpromma, Farias, Chethana, Faraj, Wanasinghe, Xu, Hyde & Gui, Mycosphere 15(1): 1036 (2024)
Index Fungorum number: IF901356; Facesoffungi number: FoF13887
Saprobic on dead twigs of Schima khasiana. Sexual morph: Ascomata 100–300 μm high, 65–200 μm diam., (x̅ = 215 × 140 μm, n = 5), immersed beneath the host epidermis, solitary or gregarious, subglobose or obpyriform, dark brown, coriaceous, ostiolate, 1–2-loculate, with few brown, septate tomentum on the outer surface. Ostioles central. Peridium 15–23 μm wide, 3–5 layered, composed of hyaline to brown cells of textura angularis. Hamathecium 2–4.5 μm wide, comprising numerous, branching, septate, cellular pseudoparaphyses constricted at the septum. Asci 58–77 × 10.5–11 μm (x̅ = 65 × 10.8 μm, n = 20), 4–8-spored, bitunicate, fissitunicate, clavate to cylindric-clavate, slightly curved, short pedicellate, apically rounded. Ascospores 13.5–16.5 × 4.5–5.5 μm (x̅ = 15 × 5.2 μm, n = 30), overlapping 1–2-seriate, broadly fusiform to ellipsoid, straight, initially hyaline to yellowish brown, aseptate to one-septate, becoming dark brown, 3-septate when mature, smooth-walled, with guttules when mature, 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 basal and apical cell of ascospore. Colonies on PDA, reaching 30 mm diameter after two weeks at 20–25 ℃, mycelia superficial, circular, umbonate, filamentous, surface smooth with fimbriate edge, velvety, grayish white, gray at margin; reverse, dark brown, white at margin.
Material examined: China, Yunnan Province, Baoshan, on dead woody twigs of Schima khasiana (Theaceae), 11 July 2020, G.C. Ren, BS09 (HKAS 122704, holotype), ex-type culture KUMCC 21-0501. ibid., living culture KUMCC 21-0502.
GenBank numbers: KUMCC 21-0501: SSU: OQ168215, LSU: OQ170862, ITS: OQ158940, tef1-α: OR613439, rpb2: OR578562; KUMCC 21-0502: SSU: OQ168216, LSU: OQ170863, ITS: OQ158941.
Notes: In the phylogenetic analyses, N. schimae formed a sister clade to N. magnoliae and N. kunmingensis with 82% ML bootstrap support 1.00 BYPP value. This species shares similar morphology with N. magnoliae in having solitary or gregarious, brown ascomata, fissitunicate, clavate to cylindric-clavate, short pedicellate, apically rounded, with minute ocular chamber asci, and ellipsoid, brown, 3-septate, guttulate ascospores. However, N. schimae is distinct from N. magnoliae in having bilocular ascomata with brown, septate tomentum, tapering pseudoparaphyses, constricted at the septum, while N. magnoliae has unilocular ascomata brown to dark brown, septate pseudoparaphyses without constricted at the septum (Wanasinghe et al. 2020b, Zhang et al. 2020a). Nigrograna schimae shares similar morphology with N. kunmingensis in having immersed, subglobose to globose ascomata with septate tomentum on the outer surface, septate, branched pseudoparaphyses, cylindrical to clavate asci, and dark brown, 3-septate ascospores when mature. However, N. schimae is distinct from N. kunmingensis in having bilocular ascomata and thinner peridium (15–23 μm vs. 20–60 μm). Sequence comparison for the ITS region between Nigrograna schima (KUMCC 21-0501) and N. magnoliae (MFLUCC 20-0020) showed a 7.1% (33/466 bp, without gaps) base pair difference in ITS region, 3.9% (36/912 bp, without gaps) base pair difference in tef1-α region, 1.8% (15/831 bp, without gaps) base pair difference in LSU region, 11% (110/999 bp, without gaps) base pair difference in rpb2 region. Sequence comparison for the ITS region between Nigrograna schima (KUMCC 21-0501) and N. kunmingensis ZHKUCC 22-0242) showed a 6.4% (30/466 bp, without gaps) base pair difference in ITS region, 3.8% (35/911 bp, without gaps) base pair difference in tef1-α region, 1.9% (16/831 bp, without gaps) base pair difference in LSU region. Herein, Nigrograna schima 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.
Figure 2. Nigrograna schimae (HKAS 122704, holotype). a Material examined. b Horizontal sections of ascomata. c‒e Vertical section through an ascoma. f Peridium. g Pseudoparaphyses. h‒k Asci. l‒n Ascospores. o Germinated ascospore. p, q Culture characters on PDA (p = from above, q = from below). Scale bars: d, e = 100 μm, f, h‒k = 30 μm, g = 20 μm, l‒o = 10 μm, p, q = 30 mm.
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