Nigropunctata yunnanensis
Nigropunctata yunnanensis G.C. Ren & K.D. Hyde, Mycosphere 15(1): 1063 (2024)
Index Fungorum number: IF 901362; Facesofungi number: FoF13896
Saprobic on dead woody twigs of Magnolia henryi. Sexual morph: Ascomata 227–288 μm high × 244–283 μm diam., (x̅ = 264 × 263 μm, n = 5), immersed to semi-immersed, papillate on the host surface, solitary or scattered, coriaceous, globose to subglobose, dark brown to dull black. Ostiole central, 70–80 μm high × 51–65 μm diam., (x̅ = 76 × 59 μm, n = 5). Peridium 8–12 μm wide, 2–3-layered, comprising light brown cells of textura angularis. Paraphyses 2–3 μm wide, hyaline, filamentous, comprising cylindrical, unbranched, septate, embedded in a hyaline gelatinous matrix. Asci 120–147 × 27–37 μm (x̅ = 133 × 32 μm, n = 20), 8-spored, unitunicate, clavate, straight or curved, apically rounded, short pedicellate. Ascospores 40–51 × 20–22.6 μm (x̅ = 44.5 × 21 μm, n = 30), overlapping unicellular, fusiform with rounded ends, straight, initially hyaline, becoming brown to dark brown at maturity, rough-walled with small guttules. Asexual morph: Undetermined.
Culture characteristics: Ascospores germinating on PDA within 24 h at room temperature (25 °C). Germ tubes produced from the apical cell of an ascospore. Colonies on PDA, reaching 40 mm diameter after two weeks at 20–25 ℃, mycelia superficial, circular, fimbriate, flat, entire edge, grayish white, reverse reddish brown.
Material examined: China, Yunnan Province, Lijiang, on dead woody twigs of Magnolia henryi (Magnoliaceae) 21 December 2019, G.C. Ren, KM16 (HKAS 122747, holotype), ex-type living culture KUMCC 21-0597.
GenBank numbers: SSU: OQ168238, LSU: OQ170888, ITS: OQ158966.
Notes: Our new isolate clustered within the Nigropunctata clade and separated from Melanographium phoenicis (MFLUCC 18-1481). Samarakoon et al. (2022) introduced Nigropunctata based on its distinct morphology and its formed independent lineage in Xylariales. The hyphomycetous Melanographium was erected based on M. Spleniosporum (Saccardo 1913). The taxonomic placement of Melanographium is unresolved, while Hyde et al. (2020b) provided sequence data for Melanographium and carried out multi-gene phylogeny, which showed Melanographium nested in Xylariales. Nigropunctata species have immersed ascomata with a thick clypeus, white or yellow ectostroma, cylindrical, short pedicel, apically rounded asci with J+, discoid or inverted, hat shaped, apical ring and uniseriate, cylindrical to broadly ellipsoidal, aseptate, ascospores with a germ slit, while our species N. yunnanensis have clavate, apically rounded asci and overlapping, fusiform ascospores with rounded ends and small guttules. In a comparison of nucleotide between our new strains (KUMCC 21 0597) and Nigropunctata bambusicola (MFLU 19-2145), N. hydei (CMUB 40018), N. nigrocircularis (MFLU 19-2130), N. saccata (MFLU 19-2144) and N. thailandica (MFLU 19-2118) identified base pair differences for LSU gene 3.2% (23/710), 3.3% (25/747), 3.5% (26/747), 8.8% (66/747) and 3.6% (27/747) respectively, ITS gene 10.8 % (57/526), 11.1% (59/529), 8.9% (44/493), 20.5% (101/493), 12.3% (66/535). Therefore, N. yunnanensis is introduced as a new species based on its distinct morphology and phylogenetic analyses of a combined LSU, ITS, and rpb2 dataset.
Figure 1. Phylogram generated from ML analysis based on LSU, ITS, and rpb2 sequence data, representing Nigropunctata. Related sequences are obtained following Samarakoon et al. (2023). Eleven strains are included in the combined analyses, which comprise 2474 characters for LSU, ITS and rpb2 alignment. Melanographium phoenicis (MFLUCC 18-1481) was used as the outgroup taxon. The best-scoring RAxML tree with a final likelihood value of -7311.307258 is presented. The matrix had 342 distinct alignment patterns, with 18.48% of undetermined characters or gaps. Estimated base frequencies were as follows: A = 0.256017, C = 0.238844, G = 0.264852, T = 0.240287; substitution rates AC = 1.458036, AG = 2.752551, AT = 1.461815, CG = 1.185047, CT = 5.554355, 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. Nigropunctata yunnanensis (HKAS 122747, holotype). a Material examined. b Appearance of ascomata on the host substrate. c, d Section of through ascoma. e Peridium. f Paraphyses. g–k Asci. l–o Ascospores. p Germinated ascospore. q, r Culture characters on PDA (q = from above, r = from below). Scale bars: c, d = 100 μm, e = 20 μm, f = 30 μm, g–k = 50 μm, l–p = 10 μm, q, r = 30 mm.
References
- Ren GC, Jayasiri SC, Tibpromma S, De Farias ARG, et al. (2024) Saprobic ascomycetes associated with woody litter from the Greater Mekong Subregion (Southwestern China and Northern Thailand). Mycosphere 15(1), 954–1082, Doi 10.5943/mycosphere/15/1/8
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