Oneirophanta lucerna, Xiao & Zhang, 2024

Xiao, Yunlu & Zhang, Haibin, 2024, Three new species and one new record of Deimatidae (Echinodermata, Holothuroidea, Synallactida) discovered in the South China Sea and the Mariana fore-arc area using integrative taxonomic methods, ZooKeys 1195, pp. 309-335 : 309

Oneirophanta lucerna sp. nov.

Figs 6 , 7

Type material.

Holotype. IDSSE-2023-0208-HS02, northern slope of the South China Sea, station SY530-HS02 (16°28.60'N, 110°18'E), depth 1389 m, 8 Feb. 2023, preserved in absolute alcohol. Paratypes. Three specimens. IDSSE-2023-0204-HS02, northern slope of the South China Sea, station SY529-HS02 (16°28.20'N, 110°43'E), depth 1393 m, 4 Feb. 2023, preserved in absolute alcohol. IDSSE-2023-0208-HS01, northern slope of the South China Sea, station SY530-HS01 (16°28.30'N, 110°43'E), depth 1389 m, 8 Feb. 2023, preserved in absolute alcohol. IDSSE-2023-0208-HS03, northern slope of the South China Sea, station SY530-HS03 (16°28.18'N, 110°43'E), depth 1392 m, 8 Feb. 2023, preserved in absolute alcohol.

Type locality.

Northern slope of the South China Sea, depth 1389 m.

Diagnosis.

Body elongated, skin smooth, color orange in vivo. Mouth anteroventral, anus posteroventral. Tentacle 19 or 20. Ventrolateral tube feet 11-14 on each body side, arranged in single rows. Midventral tube feet two and rudimentary. Dorsal papillae 15-27 on each side, placed in single rows along dorsal radius. Ventrolateral papillae 7-10 on each side, arranged in single rows. Dorsal deposits spatulated crosses, spatulated rods, and widely scattered spinous rods with branched spines. Papillae deposits with spinous rods and spatulated rods. Spatulated crosses with the arms twice divided and two types of spinous rods are in ventrum. Spinous rods and sturdy spatulated rods with open ramifications in tentacles and tube feet.

Description of holotype.

External morphology. Body elongated, dorsum inflated, ventrum flattened, slightly narrowed anteriorly (Fig. 6 ). Length in vivo 22 cm (Fig. 6B ), in ethanol 20 cm. Maximum body width 6 cm in vivo, 5.7 cm in ethanol. Color in vivo orange (Fig. 6C ), tentacle and tips of papillae and tube feet more pigmented than the body skin. Tentacle 20. Circum-oral papillae absent. Mouth anteroventral, anus posteroventral terminal. Ventrolateral tube feet 14 pairs, placed in single rows on ventrolateral ambulacrum, partly projecting horizontally from the body (Fig. 6D ). Midventral radius naked. Midventral tube feet two and rudimentary, with one placed on half the body, while the other placed on a rear quarter of the body, and several smaller tube feet close to anus. Left dorsal papillae 27, right dorsal papillae 21, measuring 1.5-5.2 cm, arranged in regular single rows along dorsal radii (Fig. 6C ). Ventrolateral papillae 9-10 on each side, measuring 2.2-3.2 cm, placed in single rows along the ventrolateral radii.

Ossicle morphology. Dorsal deposits contain spatulated crosses, spinous rods and spatulated rods. Spinous rods with irregular spines, 0.1-0.2 mm in length (Fig. 7A1, A2 ); spatulated crosses with arms 0.2-0.8 mm in length (Fig. 7A3 ); spatulated rods up to 1 mm (Fig. 7A4 ). Papillae with spinous rods 0.2-0.3 mm in length (Fig. 7B1, B2 ), and spatulated rods 0.4-0.9 mm in length, some with an extra branch from central part (Fig. 7B3 ), some bifurcated at the end (Fig. 7B4 ). Ventral body wall spatulated crosses with the arms twice divided (Fig. 7C1, C2 ) and the spinous rods of two types, one with more complex and irregularly placed spines (Fig. 7C3 ), the other with fewer and more regularly arranged spines (Fig. 7C4 ), up to 0.4 mm long. Tentacles and tube feet with similar ossicle types, spinous rods of two types, a few regularly distributed spines, 0.3-0.35 mm in length (Fig. 7D1, E1 ), irregularly shaped (Fig. 7D5, E2 ), and somewhat sturdy spatulated rods with perforated extremities that occasionally bifurcated (Fig. 7D2-D4, E3, E4 ), 0.2-0.7 mm in length.

Etymology.

The species was named after the Latin word Oneirophanta lucerna to commemorate the traditional Chinese Lantern Festival, which was relatively close to the time these specimens were collected.

Distribution.

Northern slope of the South China Sea, depths of 1389-1393 m.

Remarks.

The new species conformed to the genus Oneirophanta characterized by uncontracted the tentacles, the absence of oral papillae and tentacle discs without ramified processes. Oneirophanta lucerna sp. nov. differed from other species of Oneirophanta in possessing highly variable shaped spinous rods and ventrolateral tube feet that are only arranged in single rows, whereas, in other species (Table 2 ), they are arranged in two or three rows along ventrolateral ambulacrum: O. conservata , O. setigera , and O. mutabilis in double rows, O. idsseica sp. nov. in alternating two or three rows, and O. brunneannulata sp. nov. in three rows. The three accepted species of Oneirophanta and the other two new species in this study all have perforated plates that are absent in Oneirophanta lucerna sp. nov. This is the first record of a species in the genus Oneirophanta with mainly irregular spinous rods.

Figures

Figure 6. Oneirophanta lucerna sp. nov. (Holotype IDSSE- 2023 - 0208 - HS 02) A, B in situ images C dorsal view D ventral view. Scale bars: 5 cm.

Figure 7. SEM images of Oneirophanta lucerna sp. nov. (Holotype IDSSE- 2023 - 0208 - HS 02) A 1 - A 4 dorsal body wall B 1 - B 4 papillae C 1 - C 4 ventral body wall D 1 - D 5 tube feet E 1 - E 5 tentacles Scale bars: 50 μm (A 1 - A 2, B 1 - B 2, C 2); 100 μm (C 3, D 1 - E 5); 200 μm (A 3, A 4; B 3 - C 1).