Ophichthus lithinus (Jordan & Richardson, 1908)

Vo, Quang Van, Hibino, Yusuke & Ho, Hsuan-Ching, 2019, Ophiacantha scissionis Lee & Stöhr & Bae & Shin 2019, sp. nov., Zoological Studies (Zool. Stud.) 58 (43), pp. 1-14 : 9

Ophichthus lithinus ( Jordan and Richardson, 1908) ( Fig. 5; Table 3)

Leiuranus lithinus Jordan and Richardson, 1908: 238, fig. 3 (type locality: Cuyo, Philippines).

Ophichthus evermanni Jordan and Richardson, 1909: 172, Pl. 67 (type locality: Kauohsiung, Taiwan).

S p e c i m e n s e x a m i n e d: OIM-E.55785‒86, 2 specimens, 573‒704 mm TL, from Hàm Tử fishing harbour, Quy NhƠn city, Bình Định province, catching in trawl net at 70‒80 m, 23 Aug. 2018, collected by Q.V. Vo.

Description: Body elongate ( Fig. 5), subcircular to posterior portion of tail, then becoming slightly compressed, its depth at gill openings 33‒38 times in TL. Branchial basket slightly expanded. Head 10.4–10.6 in TL. Head and trunk 2.0 in TL. Snout short, broadly rounded when viewed from above and side; underside of snout bisected by a groove flanking the anteriormost tooth. Lower jaw included, its tip reaching to anterior margin of anterior nostril tube. Upper jaw moderately elongated, rictus well behind a vertical from posterior margin of eye. Eye moderate, situated at center of upper jaw, 3.1‒3.9 in upper jaw and 7.6–10.2 in head. Anterior nostril tubular and half of eye diameter; posterior nostril labial. A single stout barbel right at anterior base of posterior nostril on upper lip; no barbel below eye. Dorsal-fin origin behind gill opening and middle of pectoral fin, predorsal length 8.6 (8.6‒8.7) in TL. Median fins low but obvious, ending more than an eye diameter before the broadly pointed tail tip. Pectoral fin well developed with 11 rays and its length more than eye diameter, elongate but not pointed, its length 4.1‒4.4 in head length.

Head pores small but apparent. Single median interorbital (frontal) and temporal pores. Supraorbital pores 1 + 4 infraorbital pores 4 + 2, mandibular pores 5, preopercular pores 3, supratemporal pores 3. Faint rows of minute sensory papillae are present along nape, along anterior margin of orbit, and in a horseshoe-shaped pattern around base of anterior nostril. Lateral-line pores apparent; 8‒9 on head, in an arching sequence, 12 before dorsal-fin origin; 69‒70 before anus, 140–147 in total, the last ca. 2 eye diameters before tail tip.

Teeth moderately large, conical, and well separated from each other at base. Anterior part of maxilla with 4 teeth in rosette arrangement followed by sequence of: gap, two intermaxillary teeth, gap, followed by 17 or 18 uniserial vomerine teeth gradually decreasing in size. Maxillary teeth an irregularly uniserial row 19 or 20 teeth. Mandibular teeth also uniserial, with 20 or 21 in the row.

Coloration: Colour of fresh specimens: dorsal surface of head and tail covered with brown irregular blotches along dorsal surface and ending before ventral; ventral region creamy white; dorsal portion of head and gill basket brown, posterior part of eye and gill opening to pectoral-fin base pale; mandible and intermandibular region brown. Dorsal fin pale and light brown in regular intervals, anal fin, pectoral fin, and tip of caudal fin pale.