Plenodomus sinensis
Plenodomus sinensis Tennakoon, Phook. & K.D. Hyde, in Tennakoon, Phookamsak, Wanasinghe, Yang, Lumyong & Hyde, Phytotaxa 324 (1): 76 (2017)
Index Fungorum number: IF 553195; Facesoffungi Number: FoF 03235
Saprobic on dead branch of Castanopsis orthacantha and Lyonia ovalifolia. Sexual morph: Ascomata 160–400 μm high, 200–460 μm diam., (x̅ = 300 × 350 μm, n = 5), solitary, scattered, appearing as small, immersed black dots on the host, globose to subglobose, smooth, with truncate base, black, ostiolate central. Peridium 13–20 μm (x̅ = 17 μm, n = 10) at sides and base, 18–27 μm (x̅ = 24 μm, n = 10) at apex, slightly thick at the apex, composed of three layers of scleroplectenchymatous cells, inner layer comprising 2–3 cell layers of flattened, light brown cells, arranged in a textura angularis, middle layer comprising several layers of sub-hyaline cells arranged in a textura globulosa, outer layer composed of heavily pigmented, thick-walled, dark brown cells, textura angularis. Hamathecium 2.2–3.3 μm wide (x̅ = 2.9 μm, n = 10) wide, septate, cellular pseudoparaphyses, branching between the asci, embedded in a gelatinous matrix. Asci 65–85 × 11.8–13.5 μm (x̅ = 77.5 × 12.5 μm, n = 20), 8-spored, bitunicate, fissitunicate, cylindrical, apically rounded, with a distinct ocular chamber and a short pedicel. Ascospores 33–38 × 5–6.3 μm (x̅ = 35.6 × 5.6 μm, n = 20), overlapping 1–2-seriate, olivaceous to yellowish, cylindrical to subfusoid, with obtuse ends, 6–7 septa, not or slightly constricted at each septum, cell above central septum slightly wider, guttulate, thick and smooth-walled, with mucilaginous, globoid-shaped, apical and basal appendages. 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 25 mm diameter after two weeks at 20–25 ℃, mycelia superficial, circular, grey at the centre, atrovirens at the margin, smooth, downy, fimbriate; reverse atrovirens.
Material examined: China, Yunnan Province, Diqing, Xianggelila, Nixi, on dead woody twigs of Lyonia ovalifolia (Ericaceae), 31 August 2020, G.C. Ren, NX22 (HKAS 122764), living culture KUMCC 21-0644; China, Yunnan Province, Baoshan, on dead woody twigs of Castanopsis orthacantha (Fagaceae), 30 August 2020, G.C. Ren, BS39 (HKAS 122765), living culture KUMCC 21-0522.
Known distribution: Tamarindus indica (Fabaceae) and Plukenetia volubilis (Euphorbiaceae) in China (Tennakoon et al. 2017), Cirsium sp. (Asteraceae) and ferns in China (Phookamsak et al. 2019), Ageratina adenophora (Asteraceae) in China (Doilom et al. 2021), from soil in Korea (Moe et al. 2020), Castanopsis orthacantha (Fagaceae) and Lyonia ovalifolia (Ericaceae) in China.
GenBank numbers: KUMCC 21-0644: SSU: OQ168209, LSU: OQ170855, ITS: OQ158933; KUMCC 21-0522: SSU: OQ168210, LSU: OQ170856, ITS: OQ158934, tef1-α: OR613431.
Notes: Our isolate (HKAS 122764) and the holotype of Plenodomus sinensis (MFLU 17-0767) have globose to subglobose ascomata, cylindrical to subfusoid asci, 6–7-septate ascospores with mucilaginous globoid-shaped appendages at both ends, but they are slightly different; holotype differs in having flattened ascomatal base (Tennakoon et al. 2017) in addition to the prominent ostiole canal observed in the holotype. Multi-locus phylogeny shows that our collections (KUMCC 21-0644 and KUMCC 21-0522) clustered with five collections of P. sinensis. Although Plenodomus sinensis (MFLU 17-0767) clustered with P. collinsoniae (Fig. 37), P. sinensis differs in having larger asci (80–100 × 10–12 μm vs. 70 × 10 μm), longer ascospores (27–40 × 3.8–4.4 μm vs. 30–32 × 4 μm) with olivaceous to yellowish pigmentation as discussed in Tennakoon et al. (2017). Thus we confirm our collection as Plenodomus sinensis, as its characteristics are more similar to P. sinensis (MFLU 17-0767). Plenodomus sinensis appears to have a wider host range, occurring on Ageratina adenophora, Cirsium sp., Plukenetia volubilis, Tamarindus indica and ferns in China (Tennakoon et al. 2017, Phookamsak et al. 2019, Doilom et al. 2021). Our collections are the first reports of P. sinensis on Castanopsis orthacantha and Lyonia ovalifolia in China.
Figure 1. Phylogram generated from ML analysis based on SSU, LSU and ITS sequence data representing Plenodomus (Leptosphaeriaceae). Related sequences are obtained following Xu et al. (2022). Seventy strains are included in the combined analyses, which comprise 2333 characters for SSU, LSU, and ITS alignment. Didymella exigua (CBS 18.355) and D. rumicicola (CBS 68.379) were used as the outgroup taxa. The best-scoring RAxML tree with a final likelihood value of -7397.120776 is presented. The matrix had 356 distinct alignment patterns, with 32.14% of undetermined characters or gaps. Estimated base frequencies were as follows: A = 0.242656, C = 0.221744, G = 0.273758, T = 0.261843; substitution rates AC = 1.594965, AG = 3.148804, AT = 1.629126, CG = 0.839376, CT = 8.693924, 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. Plenodomus sinensis (HKAS 122764). a Material examined. b Appearance of ascomata on the host substrate. c Section of an ascoma. d Ostiole. e Peridium. f Pseudoparaphyses. g–j Asci. k–m Ascospores (red arrows indicate mucilaginous globoid-shaped apical and basal appendages). n Germinated ascospore. o, p Culture characters on PDA (o = from above, p = from below). Scale bar: c = 100 um, d = 50 um, e = 30 um, f = 10 um, g–j = 30 um, k–n = 20 um, o, p = 30 mm.
- 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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