Ophioceras cylindrosporum 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): 6599 (2024)

Index Fungorum number: IF902433; MycoBank number: MB902433; Facesoffungi number: FoF16109

Etymology – Referring to the cylindrical ascospores of this fungus.

Holotype – HKAS 131351

Saprobic on submerged decaying wood. Asexual morph: Undetermined. Sexual morph: Ascomata 420–570 µm diam, 120–150 µm high., scattered, solitary, immersed, flat ellipsoidal, black, ostiolate, with a long neck. Necks long, black, cylindrical, flexuous, mostly standing upright in the substratum. Peridium 4.8–26 µm thick, coriaceous, comprising 4–7 layers of brown to black, mostly thin-walled, polyhedral cells of textura angularis. Paraphyses 4.6–9.1 µm wide, at the base, dense, tapering towards the apex, hyaline, unbranched, septate, slightly constricted at the septum. Asci 77– 110 × 7.2–15 µm (x̅ = 96.7 × 10 µm, n = 20), 8-spored, unitunicate, cylindrical to fusiform, slightly flexuous, sessile, rounded at the apex, with an apical ring. Ascospores 40–86 × 2–3.3 µm (x̅ = 70.3 × 2.6 µm, n = 20), parallel, cylindrical to filiform, slightly curved to sigmoidal, 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 of incubation at room temperature. Mycelium dry, dense, colonies on the surface of PDA, with flat surface, regular edges, green, and white in the center. Reverse dark brown.

Material examined – China, Yunnan Province, Wenshan Zhuang and Miao Autonomous Prefecture, Bamei Town, on submerged decaying wood, 7 February 2022, W.P. Wang, S-3507 (HKAS 131351, holotype), ex-type living cultures CGMCC 3.25431 = KUNCC 23–13706.

Notes – Morphologically, Ophioceras cylindrosporum resembles O. guttulatum in having immersed ascomata with a long, cylindrical neck, cylindrical asci with an apical ring, and cylindrical, guttulate, hyaline ascospores. However, O. cylindrosporum has comparatively smaller, flat ellipsoidal ascomata (420–570 vs. 1200–1800 µm in diam, 120–150 vs. 400–600 µm in high), sessile asci, and aseptate, smaller ascospores (40–86 × 2–3.3 vs. 100–128 × 4–5 µm) distinguishing from O. guttulatum. Phylogenetic analysis showed that O. cylindrosporum constitutes a strongly supported (100% ML/1.00 PP) independent lineage basal to O. aseptatum (KUNCC 23–14570), O. dolichostomum (CMURp50, CBS 114926), O. hongkongense (HKUCC 3624 and KUNCC 23–14570), and O. submersum (MFLUCC 18–0211) (Fig. 47). Ophioceras cylindrosporum differs from O. dolichostomum and O. submersum in having aseptate, shorter ascospores (40–86 vs. 94–110 vs. 87–109 µm). Ophioceras cylindrosporum has thinner peridium (4.8–26 vs. 20–40 µm), sessile asci, and multi-guttulate ascospores, which clearly distinguish it from O. hongkongense (Tsui et al. 2001, Luo et al. 2019).

Figure 1 – Ophioceras cylindrosporum (HKAS 131351, holotype). a Ascomata on the substratum. b Vertical section of ascoma. c–e Structure of peridium. f, i–l Asci. g, h Paraphyses. m–o Ascospores. p Germinating ascospore. q, r Colonies on PDA from surface and reverse. Scale bars: b = 60 µm, c, d, f–l = 20 µm, e, m–p = 10 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.