Ramusculicola thailandica

Ramusculicola thailandica Thambug. & K.D. Hyde, Fungal Diversity, (2015)

Index Fungorum number: IF551265; Facesoffungi Number: FoF01092

Saprobic on dead woody twigs of Rhododendron rubiginosum. Sexual morph: Ascomata 115–150 μm high × 145–200 μm diam., (x̅ = 135 × 175 μm, n = 5), unilocular, immersed under the bark of the host, solitary or scattered, globose to subglobose, coriaceous, black, with an ostiole in the central. Peridium 5–16 μm thick, composed of dark brown outer layers and inner layers comprising hyaline, thick-walled cells of textura angularis. Hamathecium 1.5–2.2 μm wide, comprising numerous, unbranched, septate, hyaline pseudoparaphyses embedded in a gelatinous matrix. Asci 64–88 × 8.3–9.9 μm (x̅ = 75.8 × 9.2 μm, n = 20), 8-spored, unitunicate, long cylindrical, straight or curved, apically rounded with an ocular chamber and a short pedicel. Ascospores 25–31.5 × 4–5.2 μm (x̅ = 28.5 × 4.5 μm, n = 30), uniseriate, hyaline, fusiform with acute angular ends, 1–3-septate, slightly constricted at the septum, thick-walled, smooth, with guttules in each immature cell, and surrounded by a thin mucilaginous sheath. Asexual morph: Undetermined.

Culture characteristics: Ascospores germinating on PDA within 24 h at room temperature (25 °C). Germ tubes produced from the apical and the basal cell of ascospores. Colonies on PDA, reaching 30 mm diameter after two weeks at 20–25 ℃, mycelia superficial, circular, flat, smooth surface with shiny liquid drop, entire edge, from above light pink at the margin, grey white at the center, reverse brown.

Material examined:  Chian, Yunnan Province, Lijiang, on dead woody twigs of Rhododendron rubiginosum (Ericaceae), 30 August 2020, G.C. Ren, DQ23 (HKAS 122758), living culture KUMCC 21-0537.

Known distribution: On dead stems of Clematis sikkimensis (Ranunculaceae), Ficus septica (Moraceae), Leucaena sp. (Fabaceae) in Thailand (Jayasiri et al. 2019, Phukhamsakda et al. 2020, Tennakoon et al. 2021a), on dead woody twigs of Rhododendron rubiginosum in China.

GenBank numbers: SSU: OQ168230, LSU: OQ170879, ITS: OQ158957, tef1-α: OR613447

Notes: Ramusculicola thailandica was introduced by Thambugala et al. (2015) based on morphological and phylogenetic evidence. Our new isolate (KUMCC 21-0537) shares similar characters with R. thailandica by having unilocular, immersed, globose to subglobose ascomata with an ostiole, cylindrical asci with an ocular chamber and a short pedicel, and fusiform, 1–3-septate ascospores with guttules (Jayasiri et al. 2019, Phukhamsakda et al. 2020, Tennakoon et al. 2021a). The multi-gene phylogenetic analyses based on the combined LSU, ITS, and tef1-α sequences showed that our collection (KUMCC 21-0537) clustered with the type of R. thailandica (MFLUCC 13-0284) with 100% ML bootstrap support and 1.00 BYPP value. Based on characteristics and phylogenetic analyses, we report our collection as the first record of R. thailandica from decaying wood of Rhododendron rubiginosum in China.

Figure 1. Phylogram generated from ML analysis based on LSU, ITS and tef1-α sequence data, representing Teichosporaceae. Related sequences are obtained following Mortimer et al. (2021) and Tennakoon et al. (2021a). Fifty-nine strains are included in the combined analyses, which comprise 2318 characters for LSU, ITS and tef1-α alignment. Two strains of Torula chromolaenae (MFLUCC 17-1514 and MFLUCC 17-1504) were used as the outgroup taxa. The best-scoring RAxML tree with a final likelihood value of -9734.934654 is presented. The matrix had 677 distinct alignment patterns, with 24.3% of undetermined characters or gaps. Estimated base frequencies were as follows; A = 0.234134, C = 0.266021, G = 0.286439, T = 0.213407; substitution rates AC = 1.098317, AG = 2.075137, AT = 1.878071, CG = 1.064618, CT = 9.116965, 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.