Pseudomicrothyrium thailandicum X.Y. Zeng, S. Hongsanan & K.D. Hyde, sp. nov.

Etymology: Referring to its occurrence in Thailand.

MycoBank number: MB 556882;Index Fungorum: IF 556882; Facesoffungi number: FoF 06756; Fig. 45

Saprobic on dead leaves. Hyphae superficial, pale brown, septate, branched, loosely reticulate. Sexual morph: Thyriothecia 32–42 high × 140–160 μm diam. ( = 37 × 148 µm, n = 10), superficial, circular, light brown, solitary or gregarious, slightly carbonaceous, with a colorless basal layer, connected with hyphae, easily separated from the host surface. Upper wall light brown, comprising cells of radial arrangement of textura prismatica, darken at the central ostiole, tapering at margin. Hamathecium comprising asci inclined from the base and rim towards the central ostiole, with thin, filiform, narrow cellular pseudoparaphyses. Asci 35–40 × 10–15 μm ( = 37 × 13 µm, n = 10), 8-spored, bitunicate, fissitunicate, ovoid to obpyriform. Ascospores 13–15 × 4–5 μm (= 14 × 5 µm, n = 20), 2–3-seriate, fusiform to ellipsoidal, 1-septate, upper cell slightly wider than lower cell, not constricted at the septum, hyaline, with 2–4 apical appendages, usually with 2 large guttules in the upper cell and 2 small guttules in the lower cell, smooth-walled. Asexual morph: Undetermined.

Material examined: Thailand, Chaing Rai, MaeFahLuang University, on dead leaves of unidentified host, 3 March 2014, Xiang-Yu Zeng (MFLU 14-0286, holotype).

GenBank numbers: LSU: MT741680, SSU: MT741682.

Notes: Pseudomicrothyrium is introduced in this paper. Sequence data of P. thailandicum indicate that it forms a distinct lineage within Microthyriaceae with high support (100% ML, 1.0 PP).

Fig. 45 Pseudomicrothyrium thailandicum (MFLU 14-0286, holo- type). a, b Colony on the surface of host leaf. c Ascoma. d, e Ascoma in cross section. f Basal layer. g Pseudoparaphyses. hk Asci from young state  to mature state. lAscospores from young state  to mature state. o Germinating ascospore. p Ascoma with hyphae. Scale bars: a = 400 μm, b, p =100 μm, c, d = 50 μm, e, f = 20 μm, go = 10 μm