Leptosporella cocois Konta & K.D. Hyde, sp. nov., Index Fungorum number: IF553958

Etymology: The specific epithet refers to the host genus Cocos.

Saprobic on rachis of Cocos nucifera L. Sexual morph Ascomata 705–977 μm diameter × 209–298 μm high (x̅ = 800 × 250 μm, n = 10), solitary or aggregated, superficial, comprising black, dome shaped, raised blistering areas, subglobose, flattened at the base, ostiole central. Peridium 76–125 μm diameter (x̅ = 98 μm, n = 10), outer cells merging with the host epidermal cells, composed of dark brown to black cells of textura angularis. Hamathecium comprising numerous, 3–6 μm diameter (x̅ = 4.5 μm, n = 10), hypha-like, septate paraphyses, longer than asci. Asci 145–242 × 8–13 μm (x̅ = 187 × 10 μm, n = 20), 8-spored, unitunicate, cylindrical, long pedicellate, with a J-, wedge-shaped, subapical ring. Ascospores 99–156 × 2.5–4 μm (x̅ = 126 × 3 μm, n = 20), fasciculate, becoming spiral when mature, filiform, straight or curved, hyaline, aseptate, rounded at the apex, pointed at the base, smooth-walled, 1–4-septate when germinated. Asexual morph Undetermined.

Culture characters: Ascospores germinating on MEA within 2 days. Colonies on MEA growing, reaching 7–8.5 cm diameter after 2 months at 25°C, white at the edge, brown in the center, outwardly with strong light brown radiations. After 30 days of incubation, colonies smooth, flat, margin entire, hypha septate, branched and smooth-walled.

Material examined: THAILAND, Prachaupkhirikan Province, Sai Khu Water Fall, on dead rachis of Cocos nucifera L. (Arecaceae), 30 July 2015, Sirinapa Konta, PJK04k (MFLU 15–2349, holotype, HKAS 100705, isotype; ex-type living culture, MFLUCC 15–0816).

Notes: The phylogenetic analyses indicate that Leptosporella cocois is closely related to L. arengae, but they differ in the features of ascomata, asci, ascospores and paraphyses . Morphological differences are discussed under the latter species. Leptosporella cocois differs from L. gregaria (type species) in having larger asci with long pedicels, and filiform aseptate ascospores, while L. gregaria has smaller asci and ascospores than L. cocois, short pedicellate asci, and 7-septate ascospores. Leptosporella cocois is distinct from L. arengae in having larger ascomata, asci and ascospores without mucilaginous appendages, while L. arengae has smaller ascomata, asci and aseptate ascospores, lacking mucilaginous appendages and it differs from L. macrothecea, L. sparsa, and L. bambusae in having filiform ascospores, while L. macrothecea and L. sparsa have fusoid ascospores and L. bambusae has long fusiform ascospores (Table 1).

Fig. Leptosporella cocois (MFLU 15–2349, holotype). a Appearance of ascomata on host substrate. b Close up of ascomata. c–d Sections of ascomata. e Paraphyses. f–h Asci. i–k Ascospores. l Germinated ascospore. Scale bars: a = 1,000 μm, b = 500 μm, c–d = 200 μm, e = 10 μm, f–k = 50 μm, l = 20 μm.