Paraphaeosphaeria brachiariae Tennakoon, C.H. Kuo & K.D. Hyde, sp. nov.

MycoBank number: MB; Index Fungorum number: IF; Facesoffungi number: FoF 10803, FIGURE XX

Etymology: Name reflects the host genus, Brachiaria.

Holotype: MFLU 19-2799

Saprobic on dead leaves of Brachiaria mutica (Forssk.) Stapf (Poaceae). Sexual morph: Ascomata 60–120 μm high × 50–100 μm diam. ( = 75 × 80 µm, n = 10), solitary, scattered, coriaceous, immersed to semi-immersed, partly erumpent, visible as black dots on the host surface, unilocular, globose to sub-globose, brown to dark brown, ostiolate, with minute papilla, filled with hyaline cells. Peridium 10–20 μm wide, comprising reddish brown to dark brown, thick-walled, loosely packed cells of textura angularis, fusing at the outside indistinguishable from the host tissues. Hamathecium comprising 1.5–2.5 μm wide, cylindrical to filiform, septate, branched, pseudoparaphyses. Asci 58–65 × 11–13 μm (= 62 × 12.5 μm, n = 20), 8-spored, bitunicate, fissitunicate, clavate to cylindrical, short pedicellate, rounded at the apex and with a shallow ocular chamber. Ascospores 14–20 × 4–6 μm (= 16.5 × 5.2 μm, n = 30), overlapping, 1–2-seriate, light brown, fusiform with rounded ends, straight or slightly curved, with 1–2-septate, guttulate, rough-walled, without a mucilaginous sheath. Asexual morph: Undetermined.

Culture characteristics: Colonies on PDA, 12–15 mm diam. after three weeks at 25 °C, colonies from above: medium dense, circular, slightly raised, surface smooth with crenate edge, velvety, with smooth aspects, light brown to greenish at the margin, grey in the centre; reverse: light brown to yellowish at the margin, brown in the centre, mycelium greenish to whitish grey.

Material examined: Taiwan, Chiayi, Ali Shan Mountain, Fanlu Township area, Dahu forest, on dead leaves of Brachiaria mutica (Poaceae), 10 July 2019, D. S. Tennakoon, PC058A (MFLU 19-2799, holotype); ex-type living culture, NCYUCC 19-0342. ibid. 18 July 2019, PC058A (NCYU 19-0058, Paratype); paratype living culture, NCYUCC 19-0343.

GenBank numbers: LSU: XXXX; SSU: XXXX; ITS: XXXX.; tub2: XXXX

Notes: The morphological characteristics of our collection (MFLU 19-2799 and NCYU 19-0058) fit well within the species concept of Paraphaeosphaeria in having immersed to semi-immersed ascomata, bitunicate asci with a short pedicel and multi-septate, broadly elliptical, yellowish brown ascospores (Ariyawansa et al. 2014b, Hongsanan et al. 2020). Multi-gene phylogeny (LSU, SSU, ITS and tub) indicates that our collection (MFLU 19-2799 and NCYU 19-0058) grouped with Paraphaeosphaeria angularis with strong statistical support (99% ML, 1.00 BYPP). The asexual morph of Paraphaeosphaeria angularis was introduced by Verkley et al. (2014) from Saccharum officinarum in Brazil. A comparison of the 539 nucleotides across the ITS (+5.8S) gene region of Paraphaeosphaeria angularis (CBS 167.70) and our collection (MFLU 19-2799) shows 11 base pair differences (2.04%). We compared the 452 nucleotides across the tub gene as well and there were 12 base pair differences (2.65%). Therefore, we introduce our collection as a new species, Paraphaeosphaeria brachiariae from dead leaves of Brachiaria mutica in Taiwan.

Fig. XX Paraphaeosphaeria brachiariae (MFLU 19-2799, holotype). a, b Appearance of ascomata on substrate. c Vertical section through ascoma. d Peridium. e Pseudoparaphyses. f –i Asci. j–p Ascospores. q A germinating ascospore. r Colonies from above (on PDA). s Colonies from below (on PDA). Scale bars: c = 50 µm, d = 10 µm, e–i = 20 µm, j–q = 7 µm.