Scolecohyalosporium baoshanense

Scolecohyalosporium baoshanense G.C. Ren & K.D. Hyde. Mycosphere 15(1): 1042 (2024)

Index Fungorum number: IF 901358; Facesoffungi Number: FoF13889

            Saprobic on dead woody twigs of Dipterocarpus gracilis. Sexual morph: Ascomata 400–470 μm high, 390–460 μm diam., solitary, scattered, soft at the base and carbonaceous towards narrow apices, erumpent through the host surface, superficial, uni loculate, conical to ovoid, black, glabrous, central ostiole. Peridium 40–55 μm wide, thick walled, the outer layers composed of small, dark brown cells of textura angularis and the outer layers composed of swollen, brown cells of textura angularis. Hamathecium composed of dense, 1.7–2.5 μm wide, filamentous, branched, septate, cellular pseudoparaphyses, embedded in a gelatinous matrix. Asci 170–270 × 8.7–9.7 μm (x̅ = 221 × 9.3 μm, n = 20), 8 spored, bitunicate, fissitunicate, long cylindrical, slightly curved, apically rounded with an ocular chamber and a short pedicel. Ascospores 190–230 × 1.4–1.8 μm (x̅ = 213 × 1.6 μm, n = 20), overlapping 1–2 seriate, hyaline, filiform, spirally arranged within the ascus, narrower towards the end cell, multi septate, smooth walled, guttulate. Asexual morph: Undetermined.

Culture characteristics: Ascospores germinating on PDA within 24 h at room temperature (25 °C). Germ tubes produced from the around cell of ascospore. Colonies on PDA, reaching 30 mm diameter after two weeks at 20–25 ℃, mycelia superficial, circular, dense, flat, entire edge, gray white with granular droplets of oil, black, glistening; reverse, light brown at center, pale yellow at margin.

Material examined: China, Yunnan Province, Baoshan, on dead woody twigs of Dipterocarpus gracilis (Dipterocarpaceae), 12 July 2020, G.C. Ren, BS17 1 (HKAS 122707, holotype), ex-type living culture KUMCC 21 0507, KUMCC 21 0508.

GenBank numbers: KUMCC 21 0507: SSU: OQ168222, LSU: OQ170871, ITS: OQ158949, tef1-α: OR613442; KUMCC 21 0508: SSU: OQ168222, LSU: OQ170872, ITS: OQ158950.

Notes: In our phylogenetic analysis, new strains (KUMCC 21 0507 and KUMCC 21 0508) formed a clade sister to S. submersum (KUMCC 21 0412, KUMCC 21 0413, KUN HKAS 122242) with 100% ML bootstrap support and 1.00 BYPP value. Our isolations are similar to S. submersum in having conical to ovoid, black, glabrous ascomata, 8 spored, bitunicate, fissitunicate, long cylindrical asci and hyaline, filiform, multi septate ascospores. However, S. baoshanense differs from S. submersum in having smaller asci (170–270 × 8.7–9.7 μm vs. (200–)250–300(–370) × 7–9(–11) μm) and ascospores (190–230 × 1.4–1.8 μm vs. (230–)260–285(–315) × 1.5–2.2 μm) (Xie et al. 2022). Moreover, the culture of S. baoshanense is greyish white with black, glistening granular droplets of oil, while the culture of S. submersum is pale grey at the margin, grey to dark grey at the center. In pairwise nucleotide comparison for the ITS region between Scolecohyalosporium baoshanense (KUMCC 21-0507) and S. submersum (KUMCC 21-0412) showed a 1.6% (10/611 bp, without gaps) base pair difference in ITS region, 2.7% (25/914 bp, without gaps) base pair difference in tef1-α region. Based on its distinct morphology and the phylogeny of the combined SSU, LSU, ITS, and tef1-α dataset Scolecohyalosporium baoshanense is introduced as a new species.

Figure 1. Phylogram generated from ML analysis based on SSU, LSU, ITS, and tef1-α sequence data, representing Nigrogranaceae. Related sequences are obtained following Xie et al. (2022) and Phookamsak et al. (2023). Thirty-five strains are included in the combined analyses, which comprise 3311 characters for SSU, LSU, ITS, and tef1-α alignment. Corynespora cassiicola (CBS 100822) was used as the outgroup taxa. The best-scoring RAxML tree with a final likelihood value of 13584.772234 is presented. The matrix had 871 distinct alignment patterns, with 10.96% of undetermined characters or gaps. Estimated base frequencies were as follows: A = 0.235255, C = 0.258240, G = 0.273696, T = 0.232809; substitution rates AC = 1.077058, AG = 2.178658, AT = 1.107003, CG = 1.470438, CT = 6.032092, 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.