Ophioceras aseptatum W.P. Wang, H.W. Shen, K.D. Hyde & Z.L. Luo, in Wang, Hyde, Bao, Wanasinghe, Lin, Shen, Lu, Zhang, Su, Li, Al-Otibi, Yang & Luo, Mycosphere 15(1): 6598 (2024)

Index Fungorum number: IF902432; MycoBank number: MB902432; Facesoffungi number: FoF16108

Etymology – Referring to the aseptate ascospores of this species.

Holotype – HKAS 131369

Saprobic on submerged decaying wood. Asexual morph: Undetermined. Sexual morph: Ascomata 380–430 µm diam, 380–430 µm high., scattered, solitary, semi-immersed in the natural substratum, globose to subglobose, black, ostiolate, with a long neck. Necks long, black, cylindrical, slightly tapering towards the tip, straight or slightly flexuous, mostly stand upright in the substratum. Peridium 35–63 µm thick, coriaceous, consisting of two layered, inner layers composed of hyaline, thin-walled cells of textura angularis, becoming pale brown to black, no obvious cellular structure at outer layers. Paraphyses 8.7–12 µm wide, at the base, loose, tapering towards the apex, hyaline, unbranched, septate, slightly constricted at the septum. Asci 140–200 × 8.8–15 µm (x̅ = 168.8 × 11.2 µm, n = 20), 8-spored, unitunicate, cylindrical to fusiform, straight or slightly flexuous, short pedicellate to subsessile, rounded at the apex, with an apical ring. Ascospores 62–79 × 3.3–4.6 µm (x̅ = 71.5 × 3.9 µm, n = 15), parallel, filiform to cylindrical, slightly curved, hyaline, smooth, thinwalled, aseptate, multi-guttulate.

Culture characteristics – Ascospores germinating on PDA within 12 h, and germ tubes produced from the end. Colonies on PDA reaching 30 mm diameter after 3 weeks at room temperature. Mycelium dry, dense, colonies on the surface of PDA, with a bulbous protrusion in the center, regular edges, circular, white to brown. Reverse brown, smooth.

Material examined – China, Yunnan Province, Wenshan Zhuang and Miao Autonomous Prefecture, Bamei Town, on submerged decaying wood, 7 February 2022, W.P. Wang, S-3490 (HKAS 131369, holotype), ex-type living culture KUNCC 23–14570.

Notes – In the phylogenetic analysis, the new collection (KUNCC 23–14570) is sister to Ophioceras hongkongense (HKUCC 3624) with 78% ML/0.96 PP support (Fig. 2). Our new collection resembles O. hongkongense in having globose to subglobose ascomata with a long neck, cylindrical, short pedicellate asci, and cylindrical, guttulate, hyaline ascospores. However, it differs from O. hongkongense in having smaller ascomata (380–430 vs. 700–800 µm in diam, 380–430 vs. 500–640 µm in high), thicker peridium (35–63 vs. 20–40 µm), longer asci (140–200 vs. 100–125 µm), and aseptate, shorter ascospores (62–79 vs. 72–101 µm) (Tsui et al. 2001). Ophioceras aseptatum is therefore introduced as a new species based on morphological and phylogenetic analysis.

Figure 1 – Ophioceras aseptatum (HKAS 131369, holotype). a, b Ascomata on the substratum. c Vertical section of ascoma. d, e Structure of peridium. f Paraphyses. g–j Asci. k–n Ascospores. o Germinating ascospore. p, q Colony on PDA from surface and reverse. Scale bars: c = 100 µm, d = 30 µm, e = 50 µm, f–j = 40 µm, k–o = 20 µm.

Figure 2 – RAxML tree based on analysis of Ophioceraceae and Pararamichlordiaceae that combined LSU and ITS dataset. The combined analyses include 31 strains with 1370 characters including gaps (LSU: 839 bp and ITS: 531 bp). Bootstrap support values for maximum likelihood (ML) greater than 75% and Bayesian posterior probabilities greater than 0.95 are indicated above branches as ML/PP. The tree is rooted with Diaporthe inconspocua (CBS 133813). The new collections are indicated in red. Ex-type strains are indicated with “T” after the strain number.