Oxydothis chinensis Senan. & K.D. Hyde, sp. nov.

Index Fungorum number: IF 900462; MycoBank number: MB 900462; Facesoffungi number: FoF 14215; Fig. 1

Etymology – Species epithet based on the region where sample has been collected.

Saprobic on dead leaves of Pandanus sp. Sexual morph: Ascomata 130–175 μm high, 80–110 μm diam. (x=160×100 μm, n=10), with black, circular clypeus, solitary, scattered or rarely in groups of two, immersed under clypeus, compressed globose, dark brown, coriaceous, axis parallel to the host surface, with central, indistinct papilla. Peridium 10–18 μm (x=15 μm, n=10), outer cells merging with the host epidermal cells, comprising dark brown cells of textura angularis. Hamathecium comprises cellular, paraphyses. Asci 100–130×18–25 μm (x=120×20 μm, n=10), 8-spored, unitunicate, cylindrical to fusiform, pedicellate, with a J+, wedge-shaped, subapical ring. Ascospores 38–43×6–8 μm (x=40×7 μm, n=20), 1-seriate, upper cell longer than lower cell, fusiform, tapering gradually from the center to the ends, centrally 1-septate, not constricted at the septum, with pointed ends, hyaline, smooth-walled. Appressoria not observed. Asexual morph: Undetermined.

Culture characters – Colonies grew on PDA at 20 °C in the dark attenuated 3 cm diam., within 7 days, circular to irrigular, entire margin, flat, fluffy, with sparse wooly, aerial mycelia, surface white and reverse white to off-white.

Material examined – China, Guangdong Province, Guangzhou City, Nansha District, near BaiHui Tian reservoir, (22° 78′ 74.2″ N 113° 58.4′ 21″ E), on dead leaves of Pandanus sp. (Pandanaceae), 15 July 2021, I.C. Senanayake, GZ6 (MHZU 22-0134, holotype), ex-type culture ZHKUCC 22-0134.

GenBank numbers – ITS: OR164912, LSU: OR164957, rpb2: OR166292.

Notes – Combined ITS, LSU and tef1-α gene analysis (Fig. 2) showed that our isolate (ZHKUCC 22-0134) grouped with Oxydothis inaequalis and O. fortunei, forming a distinct clade with ML/BP=91%/0.95 statistical support. Our collection differs from Oxydothis inaequalis by having astromatic ascomata with small asci and ascospores while O. inaequalis has stromatic ascomata, long (200–285 μm) asci and long (78–88 μm) ascospores (Hidayat et al. 2006). Our collection differs from Oxydothis fortunei by its wide asci with J+, apical ring and O. fortunei has large (200–315 μm diam.), solitary or aggregated ascomata, narrow asci (9–14 μm), J- subapical ring and long (56–72 μm) ascospores (Hu et al. 2022).

Figure 1 – Oxydothis chinensis (MHZU 22-0134, holotype). a Host. b Examined material. c Ascoma on substrate. d Paraphyses. e Vertical cross section of ascomata. f, g Asci. h–k Ascospores. l Surface view of colonies. m Reverse view of colony. Scale bars: e=50 μm, f–g=40 μm, h–k=20 μm

Figure 2  – Phylogram generated from maximum likelihood analysis based on combined ITS, LSU, and tef1-α sequence data of 23 taxa, which comprised 2549 characters (ITS=697, LSU=866, tef1-α=984). The best scoring RAxML tree with a final likelihood value of − 9941.739756 is presented. The matrix had 752 distinct alignment patterns, with 36.07% of undetermined characters or gaps. Estimated base frequencies were as follows: A=0.234608, C=0.258487, G=0.267824, T=0.239080; substitution rates: AC=0.999075, AG=1.873946, AT=1.369435, CG=1.130755, CT=4.743944, GT=1.0; gamma distribution shape parameter α=0.272581. Bootstrap support for maximum likelihood (ML) equal to or greater than 50% and clade credibility values greater than 0.90 (the rounding of values to 2 decimal proportions) from Bayesian inference analysis are labelled at each node. Ex-type strains are in bold, while the new isolate is indicated in blue bold. The tree is rooted to Vialaea minutella (BRIP 56959) and V. mangiferae (MFLUCC 12-0808)