Hongkongmyces thailandica
Hongkongmyces thailandica Phukhams. & K.D. Hyde Fungal Diversity 87: 54 (2017)
Index Fungorum number: IF 628264; Facesoffungi Number: FoF 03116
Saprobic on dead woody twigs of Dipterocarpus gracilis. Sexual morph: Undetermined. Asexual morph: Coelomycetous. Conidiomata 130–150 μm high × 80–110 μm diam., (x̅ = 140 × 100 μm, n = 5), pycnidial, semi-immersed or erumpent, solitary or scattered, unilocular, coriaceous, elliptical, dark-brown to black. Ostioles central. Conidiomata wall 14–22 μm thick, 3–4-layered, composed of brown outer layers and inner layers comprising hyaline, thick-walled cells of textura angularis. Conidiophores reduced to conidiogenous cells. Conidiogenous cells 5–9 × 1.5–2.5 (x̅ = 7 × 1.8, n = 10) μm, enteroblastic, phialidic, determinate, discrete, cylindrical, hyaline, smooth-walled, arising from the stratum. Conidia 3.1–4.3 × 2.4–3 μm (x̅ = 3.8 × 2.6 μm, n = 30), hyaline, subglobose to obovoid, one-celled, aseptate, smooth-walled, verruculose, lacking a mucilaginous sheath.
Culture characteristics: Conidia germinating on PDA within 24 h at room temperature (25 °C). Germ tubes produced from the apical cell of conidia. Colonies on PDA, reaching 50 mm diameter after two weeks at 20–25 ℃, mycelia superficial, velvety, circular, flat, umbonate, entire edge, gray; reverse, atrovirens.
Material examined: China, Yunnan Province, Baoshan, on dead woody twigs of Dipterocarpus gracilis (Dipterocarpaceae), 12 July 2020, G.C. Ren, BS20 (HKAS 122708), living culture KUMCC 21-0509.
Known distribution: On decay bark in Thailand (Hyde et al. 2017).
GenBank numbers: SSU: OQ168214, LSU: OQ170860, ITS: OQ158938, tef1-α: OR613432.
Notes: Hongkongmyces thailandica was introduced as a wood-decaying saprobe based on the combined phylogeny of LSU, SSU and ITS sequence data from Thailand, and it was known only from its sexual morph. In the multi-gene phylogenetic analyses, the isolates of the asexual species (KUMCC 21-0509) formed a sister clade to the type strain of Hongkongmyces thailandica (MFLUCC 16-0406) with 100% ML bootstrap support and 1.00 BYPP value. A comparison of ITS, LSU, and tef1-α sequence data reveals no significant difference between our new isolate and H. thailandica (MFLUCC 16-0406). Our strain of Hongkongmyces thailandica and H. changchunensis share characteristics, such as phialidic, cylindrical, hyaline conidiogenous cells and obovoid, aseptate conidia; however, H. thailandica has shorter conidiogenous cells and smaller conidia than H. changchunensis (conidiogenous cells 2.6–23.5 × 1.6–4.9 μm (x̅ = 10×3 μm, n = 20), conidia 10–18 × 7–13 μm (x̅ = 13 × 10 μm, n = 43)) (Jayawardena et al. 2022). Sequence comparison for the ITS region between Hongkongmyces thailandica (KUMCC 21-0509) and H. changchunensis (CCMJ 5008) showed a 2.5% (13/526 bp, without gaps) base pair difference in the ITS region, 4.2% (35/834 bp, without gaps) base pair difference in the tef1-α region. Moreover, H. changchunensis and H. thailandica were collected from freshwater habitats, and our species, our strain of H. thailandica was collected from a terrestrial habitat on woody litter. Therefore, we report our saprobic collection KUMCC 21-0511 as the first record of the asexual species Hongkongmyces thailandica on the woody litter of Dipterocarpus gracilis in China.
Figure 1. Phylogram generated from ML analysis based on LSU, SSU, ITS, and tef1-α sequence data, representing Lindgomycetaceae. Related sequences are obtained following previous publications (Bao et al. 2021, Boonmee et al. 2021, Jayawardena et al. 2022, Yang et al. 2023). Fifty strains are included in the combined analyses, which comprise 3163 characters for LSU, SSU, ITS, and tef1-α alignment. Aigialus grandis (BCC 18419) and A. mangroveis (BCC 33563) were used as the outgroup taxa. The best-scoring RAxML tree with a final likelihood value of -13379.802355 is presented. The matrix had 857 distinct alignment patterns, with 30.81% of undetermined characters or gaps. Estimated base frequencies were as follows; A = 0.245565, C = 0.237980, G = 0 0.275632, T = 0.240823; substitution rates AC = 0.981732, AG = 3.119278, AT = 1.607343, CG = 1.127231, CT = 9.059792, 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. Hongkongmyces thailandica (HKAS 122708). a Material examined. b Appearance of conidiomata on the host substrate. c Section of a conidioma. d Conidioma wall. e Conidiogenous cells and developing conidia. f Conidia. g Germinated conidium. h, i Culture characters on PDA (h = from above, i = from below). Scale bars: c = 50 μm, d = 20 μm, e, f = 10 μm, g = 5μm, h, i = 20 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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