Ophichthus kbalanensis Hibino & Ho, 2024

Hibino, Yusuke, Ho, Hsuan-Ching & Huang, Jian-Fu, 2024, Descriptions of two new dark-body snake eels of the genus Ophichthus (Anguilliformes, Ophichthidae) from Taiwan, ZooKeys 1220, pp. 63-78 : 63-78

Ophichthus kbalanensis Hibino & Ho sp. nov.

Figs 1 , 2 ; Tables 1 , 2

Material examined.

Holotype: NMMB-P 26381 , 414 mm TL, ca 24°54.0'N, 121°56.0'E, Da-xi , Yilan, northeastern Taiwan, northwestern Pacific Ocean, 1 Jul. 2017.

Diagnosis.

A relatively short Ophichthus with the following combination of characters: head 10.3 % TL; tail 62.7 % TL; dorsal-fin origin above about middle of pectoral fin; tip of lower jaw anterior to anterior-nostril base; two simple, distally pointed protrusions along upper lip; SO 1 + 4; POM 6 or 7 + 3; teeth on jaws and vomer mostly uniserial but posterior ends of maxilla and anterior end of symphysis biserial; body dark; median fins with narrow dark margins, except the pale fin origins; 14 predorsal and 53 preanal lateral-line pores; VF 12-55 - 153.

Description.

Counts and measurements are mostly shown in Tables 1 , 2 .

Body elongate, but relatively short, subcylindrical, its depth at gill opening 11.9 in head and trunk, 31.8 in TL (Fig. 1 ); tail more compressed, tapering slowly towards tip of tail, its length 1.6 in TL. Skin of body wrinkled; relatively strong wrinkles on snout, with numerous fine longitudinal wrinkles on remaining head and body.

Head moderate, 3.6 in head and trunk and 9.7 in TL; dorsal contour of head weakly curved above eye, occipital weakly convex; branchial basket slightly swollen, its maximum depth 2.9 in head. Snout tip relatively blunt and robust, moderate in length, 6.1 in HL and 0.4 in eye. Anterior nostril a simple tube opening anteroventrally; posterior nostril a hole at inner margin of upper lip, completely covered by a wide dermal flap. Eye relatively small, 2.4 in snout length. Mouth subterminal, tip of lower jaw anterior to anterior base of anterior nostril tube. Rictus well behind posterior margin of eye. Lips smooth without small papillae; two low, small, simple, thorn-shaped protrusions, their tips pointed. Interorbital region smooth, transverse contour rounded, convex. Gill openings located ventrolaterally, upper ends slightly above middle of pectoral fin.

Sensory pores on head (Fig. 2 A ) developed but very small, not obvious; SO 1 + 4, first one (ethmoid) on ventral surface of snout; IO 3 + 3, the first behind anterior nostril base, 2 below eye, and 3 arranged in a vertical row behind eye; POM 6 (left) or 7 (right) + 3, the 6 (or seventh on right side) below rictus; ST 3, single pore on mid-temporal; and single interorbital pore. Lateral-line nearly complete, end anterior to about 1 / 2 HL before tail tip; canal on branchial basket slightly arched, 10 on branchial basket before gill opening, 14 anterior to origin of dorsal fin, 53 anterior to anus, and total 138.

Teeth moderate, conical, pointed (Fig. 2 B ); teeth on maxilla mostly uniserial, ending with an additional row consisting of 5 teeth on inner side; dentary mostly uniserial but an additional row of small teeth in outer region of symphysis anteriorly; vomerine biserial anteriorly and medially, uniserial at posterior end; 6 large teeth on intermaxillary, arranged as chevron-shape.

Dorsal and anal fins low, anal fin slightly higher than dorsal fin; both ending slightly anterior to tail tip. Dorsal-fin origin over about posterior third of pectoral fin. Pectoral fin tip weakly pointed, not lanceolate (somewhat damaged by trawl operation). Caudal fin absent, rear end of tail tip pointed.

Coloration.

Freshly caught specimen has a somewhat purplish body, darker dorsally and paler ventrally; pectoral fin dark brown and anal fin with dark brown to black margin; tail tip relatively pale (Fig. 1 A ). Preserved condition in 50 % isopropanol ethanol (Fig. 1 B ): head and body dark brown, abdomen slightly paler, densely covered with melanophores; branchial basket darker and blueish. Anterior nostril tube similar to body color; sensory pores not prominently margined. Mouth cavity dusky brown. Membrane of gill opening paler than body. Anterior portion of dorsal fin creamy white, gradually becoming dark brown similar in color to dorsal surface; narrow black margin along entire dorsal fin. Anterior portion of anal fin creamy white, gradually becoming dark brown on anterior one-third of its length, with black margin becoming broader posteriorly. Pectoral fin yellowish brown, gradually darkening posteriorly.

Etymology.

The specific name is derived from the type locality “Kbalan”, an old name of Yilan region (Kat-má-lán in Taiwanese or Cabaran in Spanish) dated back to 1300–800 years ago. Kbalan means “ people who live in the plain ” in the Taiwanese aboriginal race Kebalan. The earliest record of Kbalan occurred in the occupation of the Spanish (~ 1632) which was replaced by the Dutch East India Company in 1642.

Comparison.

The first distinctive character found in Ophichthus kbalanensis sp. nov. is the unique tooth arrangement. In most species of Ophichthus we examined, the tooth rows on jaws maintained the same number or reduced to fewer row (s) posteriorly. However, in the new species, there is a short additional row of teeth on posterior portion of upper jaw.

Secondly, the tip of lower jaw extends beyond anterior margin of base of anterior nostril tube is also quite distinct among Ophichthus species (Hibino pers. obs.). Ophichthus ishiyamorum McCosker, 2010 shares this character with O. kbalanensis , as well as the dorsal-fin origin above middle of the pectoral fin, and similar body coloration. However, O. kbalanensis sp. nov. differs from O. ishiyamorum in having a smaller head (10.3 % TL vs 14–15 % TL), more vertebrae (153 vs 130–132), maxillary teeth mostly uniserial but ending in biserial (vs mostly uniserial and biserial anteriorly), and median fins with dark margined (vs pale) ( McCosker 2010).

The tip of lower jaw is also before the anterior nostril tube in Ophichthus alleni McCosker, 2010 , several specimens of Ophichthus asakusae Jordan & Snyder, 1901 and Ophichthus urolophus (Temminck & Schlegel, 1846) ; however, they have only one or no protrusions on upper lip, much fewer total vertebrae (131–133 in O. alleni , 126–132 in O. asakusae and 134–139 in O. urolophus ), and a bicolored body with a mostly pale ventral surface ( McCosker 2010; Hibino et al. 2019 b; this study).

In Taiwan, O. kbalanensis sp. nov. is also similar to O. obtusus in the uniformly black body and vertebral count, but it can be distinguished by the different tooth arrangement on the jaws, more mandibular pores (6 or 7 vs 4 or 5), position of the end of the rictus (behind posterior margin of eye vs not behind), and two small, simple, thorn-like labial protrusions on the upper lip (vs at least anterior one fat, cauliflower-shaped protrusion with weak wrinkles) ( McCosker et al. 2012; Chiu et al. 2013; this study).

Figures

Figure 1. Ophichthus kbalanensis sp. nov., NMMB-P 26381, holotype, 414 mm TL, Da-xi, Taiwan A fresh condition B preserved condition. Arrows indicate positions of dorsal-fin origin (lefts) and anus (rights).

Figure 2. Line drawings of O. kbalanensis sp. nov., NMMB-P 26381, holotype, 414 mm TL A sensory pores on head B teeth on upper (left) and lower jaws (right). Arrows indicate interorbital (left) and mid-temporal pores (right); black solid circle indicates holes of lost tooth; and broken lines indicate concealed teeth by fleshy lips.