Roussoella chinensis sp. nov.

MycoBank number: MB; Index Fungorum number: IF; Facesoffungi number: FoF 12901; Fig. ***

Etymology: Name refers to China, the country from where this fungus was collected.

Holotype: HKAS 125555

Saprobic on a decaying pod of Wisteria sp. Sexual morph: Ascomata 110–145 μm diam, 85–105 μm high, (x̅ = 133× 98 μm, n = 10), scattered, immersed in host tissue, visible as papillate spots on the host surface, dark brown to black, subglobose to ampulliform, with ostioles. ostioles 56–77 μm diam, 50–66 μm high, (x̅ = 69× 58 μm, n = 10), Pronounced papillae, internally lined with periphyses. Peridium 6–14 μm thick, (x̅ = 9.8 μm, n = 30), composed of several layers of brown to hyaline, compressed pseudoparenchymatous cells, arranged in textura angularis. Hamathecium 1.2–2.3 μm broad, (x̅ = 1.5 μm, n = 20), composed of numerous, septate, branched, anastomosing, filiform, hyaline, pseudoparaphyses. Asci 45– 60 × 3.5–5 μm (̅x = 53 × 4.3 μm, n = 20), 8-spored, bitunicate, cylindrical to cylindric-clavate, straight to curved, short pedicellate with slightly furcate pedicel, apically rounded. Ascospores 6–8 × 2.5–3.5 μm (̅x = 7× 3 μm, n = 40), 1-seriate, ellipsoidal to fusiform, light yellowish to brown, 1-septate, slightly constricted at the septum, straight, rough-walled. Asexual morph: Undetermined

Culture characteristics – Ascospores germinating on PDA within 24 hr. Germ tubes produced from both ends of ascospores. Colonies coriaceous, pinkish white, circular, wooly from above, lower surface off white, reaching 25 mm diam. in 30 days at 25–27 °C. Mycelia are superficial, with regular edge

Material examined – CHINA, Yunnan Province, Xishuangbanna, Mengla County, Menglunzhen, decaying pod of branches, 23 May 2022, Ying Gao, BG6 (HKAS 125555, holotype), ex-type living culture, XXXX.

GenBank numbers – ITS: xxxx, LSU: xxx, SSU: xxxx

Notes – Based on our phylogenetic analysis of the combined SSU, LSU and SSU sequence data, our novel species Roussoella chinensis form distinct branches with other species and have a high support with 99% ML, 1.00 PP bootstrap support. A we introduce Roussoella chinensis as a novel taxon.

Fig. XXXXX (HKAS 125555, ex-type). a, b Ascostromata on dead branches; c, d Vertical section of ascostroma; e. Peridium; f. Ostiole; g. Pseudoparaphyses; h-l Asci; m-r Ascospores; s Germinating ascospore; t Colony on PDA (from above); u Colony on PDA (from below). Scale bars: c, d = 30 µm, e-g = 20 µm, h–l = 10 µm, m–r = 5 µm, s = 20 µm.