Oceanitis abyssalis, Nagano & Abdel-Wahab & Nakajima & Yabuki, 2024

Nagano, Yuriko, Abdel-Wahab, Mohamed A., Nakajima, Ryota & Yabuki, Akinori, 2024, Oceanitis abyssalis sp. nov., a new deep-sea fungus from sunken wood collected at the depth of 5707 m in the Northwest Pacific Ocean, Phytotaxa 663 (4), pp. 171-183 : 174

Oceanitis abyssalis Y. Nagano & Abdel-Wahab sp. nov. Figs. 2–3

MycoBank no.: MB 851445.

Diagnosis: This species differs from the other four species of Oceanitis , namely O. scuticella , O. cincinnatulum , O. unicaudatum and O. viscidulum by having unicellular ascospores that are fusiform, curved or sigmoid in shape, two type of ascospores appendages: one polar uncoiling appendage and tree-like appendages that develops throughout the ascospores’ length; semi-persistent asci and cream-colored, drop-shaped ascomata ( Dupont et al. 2009; Kohlmeyer 1977; Jones & Le Campion-Alsumard 1970a, 1970b).

Type: The Northwest Pacific Ocean, off the coast of Japan, (35°55.61′N, 144°57.87′E) under the Kuroshio Extension, on the sunken wood found on the abyssal plain at 5707 m water depths, 2 Sep 2019, Y. Nagano, holotype TNS-F-70722.

Gene sequences holotype: LC789975 (LSU), LC777827 (ITS), LC789976 (SSU).

Etymology: The epithet abyssalis refers to the abyssal plain where this species was collected.

Ascomata 1.2–1.6 mm high, 0.98–1.2 mm diam., superficial, drop-shaped, papillate, ostiolate, cream-colored, yellowish or brownish, subiculate, fleshy, single or gregarious. Ostioles 470–545 μm in length, 90–110 μm diam., ostiolar canal periphysate; periphyses 21–39 μm in length, 1–2 μm wide. Peridium 290–400 μm wide at the upper part of the ascomata, 120–160 μm wide at the lower part of the ascomata, 3-layered, forming a textura angularis; outer layer 40–50 μm wide in the upper part of the ascomata and consists of 5–7 cell layers of light-brown, thick-walled, polygonal cells, 10–20 μm wide in the lower part of the ascomata and consists of 2–4 cell layers of flattened, thick-walled cells; median layer 230–280 μm wide in the upper part of the ascomata and consists of 15–28 cell layers of hyaline, thick-walled, polygonal cells that are with large lumina and elongated to outside and small to inside, 10–20 μm wide in the lower part of the ascomata and consists of 5–9 cell layers of polygonal, thick-walled cells; inner layer 28–45 μm thick, consists of 7–11 cell layers of hyaline, flattened, parallel, thick-walled cells. Paraphyses absent, center of immature ascomata is filled with hyaline, thin-walled, polygonal pseudoparenchymatous cells which are eventually compressed by the asci. Asci 83–115 × 15–20 μm (mean =95.7 × 17.1 μm, n=25), 8-spored, unitunicate, clavate or fusiform, thin-walled, with rounded apex, semi-persistent, short pedicellate, ripening successively on an ascogenous tissue at the bottom of the ascomatal venter, becoming detached at maturity at the base and pushed upward by young asci. Ascospores 58–77 × 4–5 μm, elongate fusiform, curved or sigmoid, unicellular, hyaline, guttulate, with one apical appendage; appendages 6–16 μm long, 0.5–2 μm diam, filamentous, uncoiling, tapering toward the apex, wavy, adhering with its base to the apex of the ascospore, deciduous; occasionally ascospores develop tree-like appendages throughout its length while within the ascus or after its release ( Fig. 3 ).

Figures

FIGURE 2. Oceanitis abyssalis (TNS-F-70722, holotype). A, B: Ascomata on wood. C: Vertical section through ascoma shows the polygonal pseudoparenchymatous tissue and the ascogonial cells in the center. D: Vertical section through mature ascoma. E: Vertical section through ostiole with periphyses. F: Magnified part of the ascomatal venter shows the ascogonial tissue and the developing asci. G: Vertical section through the peridium. Bars: A 4 mm, B 1 mm, C 170 μm, D 300 μm, E–G 50 μm.

FIGURE 3. Oceanitis abyssalis (TNS-F-70722, holotype). A–E: Variously shaped asci at different stages of maturity. F–N: Variously shaped ascospores. Polar uncoiling appendage is arrowed in figures F–H. Tree-like appendages along the ascospore length is arrowed in figures L–N. Bars: A–N 10 μm.