Nigrograna thymi

Nigrograna thymi Mapook, Camporesi & K.D. Hyde Fungal Diversity 87: 68 (2017)

Index Fungorum number: IF552958; Facesoffungi Number: FoF03119

Saprobic on dead twigs of Castanopsis mekongensis. Sexual morph: Ascomata 140–250 μm high, 110–140 μm diam., (x̅ = 210 × 120 μm, n = 5), immersed to erumpent, solitary or scattered, subglobose or obpyriform, dark brown. Ostioles central, 125–145 × 50–80 (x̅ = 135 × 60, n = 5) μm, immersed, long papillate, long, hyaline hyphae with periphyses. Peridium 11–30 μm wide, 3–7-layered, slightly thin at the base, composed of dark brown outer layers and light brown inner layers of thick-walled cells of textura angularis. Hamathecium 1–2.5 μm wide, comprising filamentous, branched, septate pseudoparaphyses, constricted at septa, embedded in a gelatinous matrix. Asci 50–75 × 8–11 μm (x̅ = 64 × 9.5 μm, n = 20), 8-spored, bitunicate, fissitunicate, clavate to cylindric-clavate, slightly curved, short pedicellate, apically rounded. Ascospores 12–15 × 3.4–4.5 μm (x̅ = 13.8 × 4 μm, n = 30), overlapping 1–2-seriate, ellipsoid to fusiform, straight, initially yellowish brown, 1-septate, becoming brown, 3-septate when mature, slightly constricted at the primary median septum, guttules. 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 ascospores. Colonies on PDA, reaching 30 mm diameter after two weeks at 20–25 ℃, mycelia superficial, circular, dense, filamentous, flat, slightly raised at the center, surface smooth with fimbriate edge, velvety, light brown at the margin, white at the center; reverse, grayish brown.

Material examined: China, Yunnan Province, Lancang, Lahu Autonomous Prefecture, Hani, on dead woody twigs of Castanopsis mekongensis (Fagaceae), 20 July 2020, G.C. Ren, LGY08 (HKAS 122727), living culture KUMCC 21-0548.

Known distribution: Saprobic on dead aerial stem of Thymus oenipontanus (Lamiaceae) in Italy (Hyde et al. 2017), dead twigs attached to Magnolia grandiflora (Magnoliaceae) in China (de Silva et al. 2022), dead woody twigs of Castanopsis mekongensis (Fagaceae) in China.

GenBank numbers: SSU: OQ168218, LSU: OQ170865, ITS: OQ158943, tef1-α: OR613440, rpb2: OR578563.

Notes: In the present study, the multi-gene phylogeny indicates that our strain (KUMCC 21-0548) clustered with Nigrograna thymi (MFLUCC 14-1096) with 100% ML bootstrap support and 1.00 BYPP value (Fig. 45). However, our strain (KUMCC 21-0548) differs from MFLUCC 14-1096 in having shorter asci (50–75 × 8–11 μm vs. 90–94(–98) ×8–11 μm), ellipsoid to fusiform, 3-septate ascospores, while MFLUCC 14-1096 has fusiform to inequilateral, 4–5-septate ascospores. Hence, the sexual characteristics of N. thymi should be studied and compared with further fresh collections. Nigrograna thymi, collected from a dead aerial stem of Thymus oenipontanus in Italy, was introduced by Hyde et al. (2017) based on the combined phylogeny of LSU, ITS, SSU, and rpb2 sequence data. Taking into consideration the phylogenetic analyses, we report our saprobic strain (KUMCC 21-0548) as a new record of N. thymi on the woody litter of Castanopsis mekongensis in China.

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.