Nigrograna jinghongensis Wanas. & K.D. Hyde, sp. nov.
Index Fungorum number: IF 558601; MycoBank number: MB 558601; Facesoffungi number: FoF 09951; Fig. 1
Etymology – The specific epithet “jinghongensis” refers to the Jinghong City, Yunnan Province, China where the type was collected.
Holotype – KUN-HKAS 115776
Saprobic on woody litter. Sexual morph: Ascomata 300–400 µm high, 220–300 μm diam. (x̅=347×259 μm, n=10), perithecioid, solitary or gregarious, immersed to erumpent through host tissue, subglobose or obpyriform, uni-loculate, brown to dark brown, ostiolate. Ostiole mostly central. Peridium 10–15 μm wide at the base, 20–30 μm wide in sides, composed of angular cells, outer layer, dark brown, thick-walled cells, inner layer, hyaline with thin-walled cells. Hamathecium composed of numerous, 1.5–2.5 µm wide, filamentous, septate pseudoparaphyses. Asci 60–90×7–9 µm (x̅= 77 × 8 µm, n = 20), 8-spored, bitunicate, clavate to cylindric-clavate, short pedicellate, apically rounded, with a minute ocular chamber. Ascospores 12–15 × 4–5.5 µm (x̅=14×4.5 µm, n=30), overlapping bi-seriate, ellipsoid, yellowish-brown to brown, 1-septate, slightly echinulate, guttulate. Asexual morph Undetermined.
Culture characteristics – Ascospores germinating on PDA within 24 h and germ tubes arising from both ends. Colonies on PDA, slow growing, reaching 2 cm diam. after 4 weeks of incubation at room temperature, initially white becoming dirty white to light grey at maturity, slightly effuse, radially with an undulate edge, greyish, reverse creamy.
Material examined – CHINA, Yunnan, Xishuangbanna Dai Autonomous Prefecture, Mengla County, Menglunzhen, 21.891084° N 101.305898° E, on dead woody litter, 25 November 2020, D.N. Wanasinghe, DWX01-3 (KUN-HKAS 115776, holotype), ex-type living culture (KUMUCC 21-0035); ibid. DWX01-3-2 (KUN-HKAS 115775), living culture (KUMUCC 21-0036).
GenBank numbers – ITS = MZ493303, MZ493304, LSU = MZ493317, MZ493318, SSU = MZ493289, MZ493290, RPB2 = MZ508421, MZ508422, TEF1-α=MZ508412, MZ508413.
Notes – In the multigene phylogeny, Nigrograna jinghongensis (KUMUCC 21-0035 and KUMUCC 21-0036) clustered as a sister taxon to N. yasuniana and Nigrograna sp. (MFLUCC 17-2663) with 100% MLBS support (Fig. 2). The sequence comparison between our new strain and N. yasuniana, ITS had 0.63%, TEF1-α had 2.46% and RPB2 had 6.34% base pair variations. Nigrograna yasuniana was previously documented as an endophyte on Conceveiba guianensis (Euphorbiaceae) from Ecuador. Unfortunately, sufficient morphological data are not available for N. yasuniana to compare with our novel taxon. Based on its morphology and phylogenetic placement, we therefore, introduce Nigrograna jinghongensis as a new species (Fig. 1).
Figure 1 – Nigrograna jinghongensis (KUN-HKAS 115776, holotype). a–c Appearance of ascomata on host surface. d Longitudinal section of an ascoma. e Section of the peridium cells. f Pseudoparaphyses. g–i Asci. j–o Ascospores. Scale bars: d=100 μm, e, g–i=20 μm, f=5 μm, j–o=10 μm
Figure 2 – Phylogram generated from the best scoring of the RAxML tree based on combined SSU, LSU, ITS, TEF1-α and RPB2 sequence dataset to indicate the new species Nigrograna jinghongensis and related species in Nigrogranaceae. Thirty-three strains are included in the combined analyses which comprise a total of 4372 characters. Occultibambusa bambusae (MFLUCC 13-0855) and O. chiangraiensis (MFLUCC 16-0380) are selected as the outgroup taxa. The best RAxML tree with a final likelihood value of − 16022.187073 is presented. RAxML analysis yielded 1068 distinct alignment patterns and 26.01% of undetermined characters or gaps. Estimated base frequencies were as follows: A=0.24908, C=0.245478, G=0.267145, T=0.238298, with substitution rates AC=1.477319, AG=4.369095, AT=1.2688, CG=0.859595, CT=11.229756, GT=1.000000; gamma distribution shape parameter alpha=0.579103. Bootstrap support values for maximum likelihood (MLBS, left) equal to or greater than 60% is given above the nodes. Ex-type strains are in bold and newly generated sequences are in blue