Oxydothis filiforme L.W. Li & Jian K. Liu, sp. nov.

Index Fungorum number: IF 902399; Mycobank number: MB 902399; Facesoffungi number: FoF 16062; Fig. 1

Etymology – The name reflects the shape of Asci

Holotype – HKAS 125889

Saprobic on decaying branches of Trachycarpus fortunei. Sexual morph: Ascomata 283–292 × 305–323 μm (x̅= 287.5 × 314 μm, n = 10), solitary or aggregated, immersed, under slightly raised areas, visible as blister-like regions on the host surface, long axis horizontal to that of the host, ostiolate. Ostioles 102–158 μm wide, eccentric, conspicuous, curving upwards and piercing the host cuticle. Peridium 31–38.5 (x̅=35 μm, n=10), comprising 8–10 layers of brown-walled cells of textura angularis. Hamathecium few, filamentous, septate, tapering distally. Asci 102–128×11–13 μm (x̅=115×12 μm, n=20), 8-spored, fasciculate, unitunicate, cylindrical-clavate, pedicellate, with a J+, wedge-shaped, subapical ring, 2.6–3.6 μm high, 3.2–3.5 diam, and faint canal leading to the tip. Ascospores 67.5–77×4.5–5.5 μm (x̅=72×5 μm, n=20), filiform, tapering towards both ends, centrally 1-septate, not constricted at the septum, hyaline, with multi-guttule in each cell, smooth-walled. Asexual morph: Not observed.

Culture characteristics – Ascospores germinating on PDA within three days. Colonies on PDA, white to smoky-grey, rough on the surface, margins smooth, dense at the center, with fairly fluffy.

Material examined – China, Sichuan Province, Chengdu, University of Electronic Science and Technology of China (UESTC) campus (Qingshuihe), on the dead branch of Trachycarpus fortunei (Hook.) H. Wendl. (Arecaceae), 25 Nov. 2020, W.L. Li, WD25 (HKAS 125889, holotype; HUEST 22.0062, isotype), ex-type living cultures CGMCC 3.24160= UESTCC 22.0061. WD25b (HUEST 22.0063, paratype), living cultures UESTCC 22.0062.

GenBank numbers – UESTCC 22.0061: ITS: OQ171260; LSU: OQ171229; SSU: OQ171231. UESTCC 22.0062: ITS: OQ171261; LSU: OQ171230; SSU: OQ171231.

Notes – In the phylogenetic analysis, our stain of Oxydothis filiforme (UESTCC 22.0061, UESTCC 22.0062) clustered together with the ex-type strain of O. inaequalis with absolute bootstrap support (ML 100%). Oxydothis filiforme is morphologically similar to O. inaequalis as of the report by Hidayat et al. (2006) with immersed, ellipsoid ascomata and fusiform, 1-septate, hyaline ascospores. However, O. inaequalis differs from O. filiforme in having longer asci (200–285 vs. 102–128) and larger ascospores (78–87.5×5–7.5 μm vs. 67.5–77×4.5–5.5 μm). Additionally, ascospores of O. inaequalis are arranged 1–2 seriate or partially overlapping within asci but arranged in bundles in those of O. filiforme. Oxydothis filiforme resembles previously known but without molecular data species O. maculosa and O. luteaspora in having filiform, straight, 1-septate ascospore, J+asci and their ascomata parallel to the host surface. However, Oxydothis filiforme has shorter and thinner ascospores than O. luteaspora (long: 67.5–77 μm vs. 84–100 μm; wide: 4.5–5.5 μm vs. 6.5–8.5 μm). Oxydothis maculosa can be distinguished from O. filiforme in its ascal ring size (2–2.5×2–3 μm vs. 2.6–3.6×3.2–3.5 μm) and morphology (discoid vs. rectangular).

Figure 1 – Oxydothis filiforme (HKAS 125889, holotype): a–c. Ascomata on host substrate. d, e Transverse section of ascomata. f Peridium. g, h, j Asci. i Asci in Congo red. k J+reaction of apical ring in Melzer’s reagent. l–n Ascospores. o Ascospores in Congo red. p Germinated ascospore. q Colonies from above (on PDA). r Colonies from below (on PDA). Scale bars: d, e, g=100 μm, f, h–p=10 μm