Acrocalymma pterocarpi
Acrocalymma pterocarpi Jayasiri, E.B.G. Jones & K.D. Hyde, Mycosphere 10(1): 20 (2019)
Index Fungorum number: IF555528; Facesofungi number: FoF0522
Saprobic on dead woody twigs of Parashorea chinensis. Sexual morph: Ascomata 110–240 μm high, 35–120 μm diam., (x̅ = 195 × 70 μm, n = 5), semi-immersed, clustered, sometimes solitary, scattered, globose to subglobose, elliptical or obpyriform, uni-loculate, coriaceous, black. Ostioles central, 65–95 μm long, 35–63 μm diam., (x̅ = 74 × 49 μm, n = 5). Peridium 7–11 μm wide, 2–3-layered, composed of dark brown outer layers and hyaline inner layers, thick-walled cells of textura angularis. Hamathecium 1.5–2.5 μm wide, comprising numerous, branching, septate, hyaline pseudoparaphyses, embedded in a gel matrix. Asci 53–76 × 9–11 μm (x̅ = 65.5 × 9.7 μm, n = 20), 8-spored, bitunicate, fissitunicate, clavate to cylindric-clavate, slightly curved, with a truncated pedicel, apically rounded. Ascospores 16–19 × 3.7–4.3 μm (x̅ = 18.1 × 4 μm, n = 30), overlapping 1–2-seriate, hyaline, fusiform with acute ends, slightly curved, 1–3-septate, slightly constricted at the septum, smooth-walled, large guttules in each cell. Asexual morph: Undetermined.
Culture characteristic: 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 50 mm diameter after two weeks at 20–25 ℃, mycelia superficial, circular, marginal hyphae emission, flat, gray with white spots, producing pigmentation on PDA; reverse, black.
Material examined: China, Yunnan Province, Xishuangbanna, on dead woody twigs of Parashorea chinensis (Dipterocarpaceae), 15 December 2019, G.C. Ren, XS24 (HKAS 122777), living culture KUMCC 21-0675.
Known distribution: On a fallen pod of Pterocarpus indicus (Fabaceae) in Thailand (Jayasiri et al. 2019), dead twigs attached to the Magnolia sp. in China (de Silva et al. 2022), dead twigs of Bidens sp. (Chethana et al. 2023) on dead woody twigs of Parashorea chinensis (Dipterocarpaceae) in China (This study).
GenBank numbers: LSU: OQ170831, ITS: OQ158911, SSU: OQ168191, tef1-α: OR613417.
Notes: Acrocalymma pterocarpi was introduced by Jayasiri et al. (2019) from a fallen pod of Pterocarpus indicus in Thailand. In the phylogenetic analysis, our isolate (KUMCC 21-0675) clustered with A. pterocarpi with 97% ML bootstrap support and 1.00 BYPP value. A pairwise nucleotide comparison showed that our isolate (KUMCC 21-0675) differs from A. pterocarpi (MFLUCC 17-0926) in 4/901 bp of tef1-α (0.44%, without gaps) and 5/464 bp of ITS (1.08% without gaps). Our collection (KUMCC 21-0675) resembles A. pterocarpi (MFLUCC 17-0926) in having globose to subglobose, dark brown to black ascomata, cylindrical, hyaline asci (65.5 × 9.7 μm vs 70 × 10 μm), fusiform, 1–3-septate ascospores (18.1 × 4 μm vs 19.5 × 4 μm) (Jayasiri et al. 2019). Therefore, we introduce our collection as the first record of A. pterocarpi from Parashorea chinensis (Dipterocarpaceae) in China.
Figure 1. Phylogram generated from ML analysis based on SSU, LSU, ITS and tef1-α sequence data, representing Acrocalymmaceae. Related sequences are obtained following Jayasiri et al. (2019), Mortimer et al. (2021) and Calabon et al. (2023b). Thirty-seven strains are included in the combined analyses, which comprise 3301 characters for SSU, LSU, ITS and tef1-α alignment. Boeremia exigua (CBS 431.74) and B. foveata (CBS 341.67) were used as the outgroup taxa. The best-scoring RAxML tree with a final likelihood value of -9402.946202 is presented. The matrix had 563 distinct alignment patterns with 39.03% of undetermined characters or gaps. Estimated base frequencies were as follows; A = 0.245541, C = 0.224280, G = 0.269962, T = 0.260217; substitution rates AC = 1.707655, AG = 3.127362, AT = 2.668674, CG = 1.135340, CT = 8.212547, 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. Acrocalymma pterocarpi (HKAS 122777). a Material examined. b Appearance of ascomata on the host substrate. c Section of an ascoma. d. Ostioles. e Peridium. f Pseudoparaphyses. g–k Asci. l–o Ascospores. p Germinated ascospore. q, r. Culture characters on PDA (q = from above, r = from below). Scale bars: c = 100 μm, d, e = 30 μm, f–k = 20 μm, l–p = 10 μm, q, r = 30 mm.
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