Bascanichthys kabeyawan Hibino & Ho, 2022

Hibino, Yusuke, Yamashita, Kenta, Sakurai, You & Ho, Hsuan-Ching, 2022, Two new species of the snake eel genus Bascanichthys (Anguilliformes: Ophichthidae) from the northwestern Pacific, Zootaxa 5189 (1), pp. 103-113 : 104-106

Bascanichthys kabeyawan Hibino & Ho , sp. nov.

English name: Kabeyawan Sand Eel

Figs. 1‒2 ; Table 1

urn:lsid:zoobank.org:act:E76966BF-BEB0-4C89-8686-0E661A23D84F

Holotype. NMMB-P 36052, 526 mm TL, ca. 22°03'42.3"N 120°42'23.6"E, mouth of Shi-Chong River , Pingtung, southwestern Taiwan, trap net (fyke net), 8 Jan. 2022.

Diagnosis. An extremely elongate species of Bascanichthys with the following combination of characters: head 4.6% TL; tail 52.3% TL; body depth at gill opening 1.1% TL; predorsal-fin length 58.4% HL; snout length 10.9% HL; body bicolored, head without bands; lateral-line pores anterior to anus 104; vertebral formula 4-103-224; and dorsal-fin origin slightly behind middle of head and above fourth lateral-line pore.

Description. Counts and measurements are shown in Table 1 . Body extremely thin and slender ( Fig. 1 ), nearly circular in cross-section to anterior part of tail, then becoming slightly compressed laterally, its depth at gill opening 92 times in TL. Skin mostly smooth on entire body, except for slightly wrinkling on cheek and anterior branchial basket regions; anus a long slit, situated at around middle of total length, preanal length 2.1 in TL. Head small; branchial basket well-expanded, clearly deeper than trunk, its deepest depth 3.1 times in HL.

Snout short, bluntly pointed from dorsal view and slightly pointed from side, its length 9.2 in HL; posterior half of snout bisected by a deep groove ventrally (2 flashy vertical lamellae present). Eye small, its center behind mid-upper jaw, posterior margin of eye clearly before rictus, its diameter 4.0 in upper jaw length and 19.9 in HL; interorbital space narrow, its width 1.4 times eye diameter and 14.0 in HL; interbranchial space narrow, its width 13.4 in HL; numerous papillae present on anterior half of head, including snout, lips, chin, cheek, top of skull and interorbital space; anterior nostril tubular, extending rather downward than forward from the snout; posterior nostril a hole along upper lip, covered by broad flap extending slightly below edge of mouth gape, opening towards posteroventrally; a single compressed fleshy barbel in front of the posterior nostril. Rictus situated clearly behind a vertical through posterior margin of eye; no short fold at posterior end of mouth gape; lower jaw short, tip extends to near the posterior margin of anterior nostril tube, distance from tip of snout to anterior end of lower jaw slightly longer than eye diameter; gill opening lateral, located ventral half of body.

Sensory pores on head and body large and well apparent ( Fig. 2A ); supraorbital pores 1 (ethmoid)+3 on dorsal surface of snout and interorbital space, 4th pore above middle of eye; infraorbital pores 3+2 (right) or 3+3 (left), 1 above the barbel (in front of posterior nostril), 2 below eye along upper jaw, and 2 (right) or 3 (left) in a vertical row behind eye; mandibular pores 4, anterior 3 along lower jaw and the 4th slightly behind rictus; preopercular pores 2; interorbital pore 1; supratemporal pores 3 (single mid-temporal pore). A row of tiny sensory papillae on outer surface of gill basket. Lateral-line pores relatively large, opening clearly below the lateral-line canal, forming waveshape; 3 pores before dorsal-fin origin; 10 before gill opening, forming an arch; 104 anterior to anus; total pores 213, the last at about 1/2 HL in advance of tail tip.

All teeth ( Fig. 2B ) moderately small, conical and closely spaced; intermaxillary with 3 large teeth arranged in a triangle, followed by a gape and then single row of 11 small teeth on vomer; maxilla with single row of teeth on anterior third, then biserial on the rest, 16 teeth on outer row and 21 on inner row; mandible with single row of 21 teeth on each side.

Dorsal and anal fins low but obvious, ending at near tip of tail; dorsal-fin origin slightly behind a vertical through middle of head, above fourth lateral-line pore, 0.4 HL before gill opening; pectoral fin minute, flap-like with about 3 short rays, located at upper corner of gill opening, its length 2.6% HL and base height 5.4% HL (best seen with magnification).

Color in both fresh and preserved condition ( Figs. 1A‒C ): head uniformly grayish black with ventral surface slight paler; body grayish black dorsally and uniformly pale on ventral surface, forming clearly bicolored with the boundary slightly below lateral line; lateral-line pores and adjacent regions without pigments; all fins pale without pigments, except for some dark pigments on pectoral fin; a small cluster of pigments in front of anus; mouth cavity pale with few dark pigments.

Etymology. The scientific name kabeyawan (Taiwanese: ku-piah-uan), used as a noun, is an old name of the type locality Checheng, a territory of aboriginal Paiwan people documented in the Dutch occupation period (1624‒ 1662).

Distribution. Currently only known from the single specimen collected from mouth of Shih-chong River, Pingtung, southern Taiwan at depth about 1 meter.

Ecological note. The specimen was collected by trap net operated by a local fisherman who targeted on glass eel of Anguilla spp. It was collected together with other snake eels, such as Lamnostoma sp. and Ophichthus sp. , and was likely chasing the fish larvae to the river mouth.

Figures

FIGURE 1. Bascanichthys kabeyawan Hibino & Ho, sp. nov., holotype, NMMB-P36052, 526 mm TL, Pingtung, southern Taiwan. A. Dorsal view. B. Ventral view. C. Lateral view of head. Photo by P.-N. Lee.

FIGURE 2. Drawings showing the head pores and tooth pattern of Bascanichthys kabeyawan sp. nov., from the holotype. A, head pores; B, tooth pattern on upper jaw (left) and lower jaw (right). Arrows indicate the interorbital pore (left) and medtemporal pore (right).