Oxydothis garethjonesii Konta & K.D. Hyde, sp. nov., Index Fungorum number: IF552541
Etymology: The specific epithet is named after Professor E.B.G. Jones in recognition of his contribution to mycology on his 80th birthday.

Saprobic on petiole of Eleais Jacq. (Arecaceae). Sexual morph: Ascomata 221–348 μm diam. (x̅ = 293 μm diam., n = 40, up to 400 μm), solitary or aggregated, mostly solitary when young, becoming grouped at maturity, immersed, comprising slightly raised blistering areas through the host tissue, axis oblique or perpendicular to the host surface, with central papilla, 118–133 μm high × 122–141 μm diam. (x̅ = 123 × 131 μm, n = 5), in transverse section, globose to subglobose, darker at the central region, light towards the outer darker rim on the host surface. Peridium 15–34 μm (x̅ = 25 μm, n = 10) thick-walled, outer cells merging with the host epidermal cells, dark brown to black, walled cells of textura angularis. Asci 210–229 × 14–21 μm (x̅ = 216 × 19 μm, n = 10), 8-spored, fasciculate, unitunicate, cylindrical-clavate, pedicellate, with a J+, wedge-shaped, subapical ring. Ascospores 47–50 × 3–5 μm (x̅ = 49 × 4 μm, n = 20), 2–4-seriate, filiform to fusiform, tapering gradually from the center to the ends, centrally 1-septate, not constricted at the septum, with blunt to pointed ends, hyaline, with large guttules in each cell when immature, and lack in maturity, smooth-walled. Appressoria 15–36 μm high × 18–20 μm diam. (x̅ = 23 × 19 μm, n = 10) solitary, hyaline, irregular in shape, thick-walled. Asexual morph: Undetermined.

Culture characters: Ascospores germinating on MEA within 24 hours and germ tube producing appressoria. Colonies on MEA, smoky-grey to dark green, margins smooth, dense at the center, with fairly fluffy, as double rings, hyphae, septate, branched, smooth-walled.

Material examined: THAILAND, Krabi, on petiole and rachis of Eleais sp. (Arecaceae), 3 December 2014, S. Konta, KBM01c (MFLU 15-0033, holotype); Ibid. (HKAS95038); ex-type living culture, MFLUCC 15-0287.

Notes: Oxydothis garethjonesii is similar to O. megalospora J. Fröhl. & K.D. Hyde and O. daemonoropsicola J. Fröhl. & K.D. Hyde in characteristics of ascospores. It however differs from these species in host, the size of ascomata and ascospores, and shape of ascal apical ring (Fröhlich & Hyde 2000). Oxydothis garethjonesii is phylogenetically related to O. frondicola (95% ML, 0.99 PP) and O. daemonoropsicola as basal branches (52% ML, 0.93 PP).

Fig. Oxydothis garethjonesii (holotype) a. Host substrate. b–c. Close up of ascomata. d. Section of ascoma. e. Peridium. f. Asci. g–h. Immature asci. i. Mature Ascus. j–p. Ascospores. q. J+ reaction of apical ring in Melzer’s reagent. r. Germinating ascospore. s–u. Appressoria. Scale bars: b = 1000 μm, c = 500 μm, d = 50 μm, e = 10 μm, f–p, r = 50 μm, q = 5 μm, s–u = 10 μm.