Aurantiascoma minimum

Aurantiascoma minimum (Mugambi, A.N. Mill. & Huhndorf) Thambug. & K.D. Hyde, in Thambugala et al., Fungal Diversity, (2015)

Index Fungorum number: IF 551263; Facesoffungi Number: FoF 551263

Saprobic on dead woody twigs of Shorea assamica. Sexual morph: Ascomata 250–280 μm high × 250–300 μm diam., (x̅ = 260 × 280 μm, n = 5), immersed under the bark of the host, solitary or clustered, subglobose to globose, coriaceous, black, with an ostiole in the central. Peridium 20–30 μm thick, 3–4-layered, composed of dark brown outer layers and inner layers comprising hyaline, thick-walled cells of textura angularis. Hamathecium 1.5–2 μm wide, comprising numerous, branched, septate, hyaline pseudoparaphyses, embedded in a gelatinous matrix. Asci 125–147 × 14–17.5 μm (x̅ = 137 × 16 μm, n = 20), 8-spored, unitunicate, long cylindrical, straight or curved, apically rounded with an obvious apical ring and a short pedicel. Ascospores 34–40 × 6.9–8 μm (x̅ = 37.5 × 7.5 μm, n = 30), uniseriate, hyaline, fusiform with acute angular ends, 1-septate, slightly constricted at the septum, with guttules in each cell, thick-walled, smooth, with a small mucilaginous sheath that extends at the tips of the spore. 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 ascospore. Colonies on PDA, reaching 40 mm diameter after two weeks at 20–25 ℃, mycelia superficial, circular, flat, smooth surface with shiny liquid drop, entire edge, from above grey at the margin, grayish white at the center; reverse, dark brown at edge, grey white at center.

Material examined: China, Yunnan Province, Baoshan, on dead woody twigs of Shorea assamica (Dipterocarpaceae), 10 August 2020, G.C. Ren, BS25 (HKAS 122710), living culture KUMCC 21-0513.

Known distribution: On decorticated woody branches of unidentified plant in Costa Rica, Kenya and the USA (Mugambi & Huhndorf 2009), on dead woody twigs of Shorea assamica in China (This study).

GenBank numbers: SSU: OQ168227, LSU: OQ170876, ITS: OQ158954, tef1-α: OR613445.

Notes: Thambugala et al. (2015) synonymized Misturatosphaeria minima under Aurantiascoma based on the phylogenetic analyses of the combined LSU, SSU, ITS, and tef1-α sequence data. Aurantiascoma minimum was introduced by its sexual morph, which is characterized by pyriform to subglobose ascomata, cylindrical-clavate asci with an ocular chamber, and fusiform, 1-(–3)-septate ascospores with a small mucilaginous sheath that extends at the tips of the spore (Mugambi & Huhndorf 2009, Thambugala et al. 2015). Aurantiascoma minimum was found on decorticated woody branches from Costa Rica, Kenya and the USA (Mugambi & Huhndorf 2009). The ascomata, asci and ascospores of this new collection (KUMCC 21-0513) is similar to A. minimum. The multi-gene phylogenetic analysis based on the combined LSU, ITS, and tef1 α sequences showed that our collection (KUMCC 21-0513) forms a monophyletic group with the type of A. minimum (GKM 1690) with 98% ML bootstrap support and 1.00 BYPP value. Based on morphological characteristics and phylogenetic analysis, we report our collection as the first record of A. minimum from decaying wood of Shorea assamica 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.