Pseudolachnella lancangensis
Pseudolachnella lancangensis G.C. Ren & K.D. Hyde, Mycosphere 15(1): 1056 (2024)
Index Fungorum number: IF901361; Facesofungi number: FoF13895
Saprobic on dead woody twigs of Castanopsis mekongensis. Sexual morph: Ascomata 215–320 μm high × 225–310 μm diam., (x̅ = 270 × 260 μm, n = 5), perithecial, immersed, solitary or scattered, globose to subglobose, yellowish orange. Ostioles central. Peridium 14–25 μm wide, composed of hyaline cells of textura angularis with guttules. Paraphyses 2–3 μm wide, comprising cylindrical, unbranched, aseptate, embedded in a hyaline gelatinous matrix. Asci 95–124 × 7.3–9.4 μm (x̅ = 106 × 8.3 μm, n = 20), 8-spored, unitunicata, cylindrical, straight or curved, rounded at the apex, short pedicellate. Ascospores 18.4–22.5 × 4.9–5.3 μm (x̅ = 20 × 5.1 μm, n = 30), overlapping uniseriate, fusiform, hyaline, 3-septate, constricted at the septum, tapering towards the ends, guttulate, thin and smooth-walled, with a mucilaginous sheath. Asexual morph: Undetermined.
Culture characteristics: Ascospores germinating on PDA within 24 h at room temperature (25 °C). Germ tubes produced from both ends. Colonies on PDA, reaching 10–20 mm diameter after two weeks at 20–25 ℃, mycelia superficial, irregular, white, floccose, umbonate, flat, lobate edge, reverse white, light yellow at center.
Material examined: China, Yunnan Province, Lancang, Lahu Autonomous Prefecture, Hani, on dead woody twigs of Castanopsis mekongensis (Fagaceae), 20 July 2020, G.C. Ren, LGY34 (HKAS 122737, holotype), ex-type living culture KUMCC 21-0565.
GenBank numbers: LSU: OQ170885, ITS: OQ158963, tef1-α: OR613448.
Notes: Pseudolachnella lancangensis (KUMCC 21-0565) forms a separate clade sister to P. scolecospora (MAFF 244379) and P. asymmetrica (MAFF 244366) with 100% ML bootstrap support and 1.00 BYPP value. Pseudolachnella lancangensis represents the first record of a sexual morph for this genus and we were unable to isolate the asexual morph in culture. Therefore, we compared the morphology of P. lancangensis with Chaetosphaeriaceae family descriptions for characters, including astromatic perithecia, cylindrical asci, and transversely septate ascospores (Réblová et al. 1999, Li et al. 2016). Sequence comparison for the ITS region between Pseudolachnella lancangensis (KUMCC 21-0565) and P. scolecospora (MAFF 244379) showed a 1.6% (8/490 bp, without gaps) base pair difference in ITS region, 1.4% (13/903 bp, without gaps) base pair difference in the tef1-α region. Sequence comparison for the ITS region between Pseudolachnella lancangensis (KUMCC 21-0565) and P. asymmetrica (MAFF 244366) showed a 1.6% (8/490 bp, without gaps) base pair difference in ITS region, 0.7% (6/903 bp, without gaps) base pair difference in tef1-α region. Therefore, based on morphological characteristics and phylogenetic analysis, we report our collection as a new species from the decaying wood of Castanopsis mekongensis in China.
Figure 1. Phylogram generated from ML analysis based on LSU, ITS, and tef1-α sequence data, representing Chaetosphaeriaceae. Related sequences are obtained following Hashimoto et al. (2015) and Li et al. (2016). Twenty-one strains are included in the combined analyses, which comprise 1292 characters for LSU, ITS, and tef1-α alignment. Pseudolachnea hispidula (MFLUCC 15-0583) was used as the outgroup taxon. The best-scoring RAxML tree with a final likelihood value of -6450.343293 is presented. The matrix had 287 distinct alignment patterns, with 6.83% of undetermined characters or gaps. Estimated base frequencies were as follows; A = 0.227964, C = 0.290149, G = 0.282030, T = 0.199857; substitution rates AC = 1.213122, AG = 1.620223, AT = 0.842547, CG = 0.887486, CT = 9.028758, 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. Pseudolachnella lancangensis (HKAS 122737, holotype). a Material examined. b Appearance of ascomata on the host substrate. c Section of an ascoma. d Peridium. e Paraphyses. f–i Asci. j–n Ascospores. o Ascospore with mucilaginous sheath in Indian ink. p Germinated ascospore. q, r Culture characters on PDA (q = from above, r = from below). Scale bars: c = 150 μm, d, f–i = 50 μm, e = 15 μm, j–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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