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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.

Bascanichthys ryukyuensis Hibino, Yamashita & Sakurai, sp. nov. New standard Japanese name: Kazura-umihebi New English name: Vine-like Sand Eel Figs. 3‒4; Table 1 urn:lsid:zoobank.org:act: 4B91D8E3-F13A-4B4A-9FDC-6F4F51049E26 Bascanichthys sp.: Hibino et al. 2021: 17, fig. 6a (Okinawa-jima Island, Japan). Holotype. FRLM 52250, 627 mm TL, female, Yakena, eastern coast of Yokatsu Peninsula, Okinawa-jima Island, Ryukyu Islands, Japan, stranded specimen found at beach (0–1 m depth) around seagrass bed, 26 Jan. 2016, coll. K. Yamashita. Paratype. FRLM 52251, 516 mm TL, male, collected with holotype. Diagnosis. An extremely elongate species of Bascanichthys with the following combination of characters: head 3.7–4.3% TL; tail 43.3–44.2% TL; predorsal-fin length 40.7–45.4% of head length; snout length 11.3–13.1% of head length; body pale brown, head without distinct dark bands after preservation; lateral-line pores anterior to anus 114–118; total vertebrae 207–216, mean vertebral formula 2-116-212; and dorsal-fin origin slightly before middle of head and before first lateral-line pore. Description. Counts and measurements are shown in Table 1. Body extremely elongate (Fig. 3A), subcylindrical, tail laterally compressed posteriorly, its depth at gill opening 83‒91 times in TL. Skin generally smooth, with weak longitudinal wrinkles dorsally; tail shorter than head and trunk, preanal length 1.8 in TL. Head small, skin with many longitudinal wrinkles except snout; dorsal contour smoothly curved; branchial basket convex, well-expanded, its deepest depth 2.4–2.7 times in HL. Snout stout and broad, tip weakly pointed and relatively pointed from dorsal view (Fig. 3B, C), its length 7.6–8.8 in HL; posterior half of snout bisected by a deep groove ventrally; interorbital region smooth, slightly convex. Eye small, positioned about mid-jaw, its diameter 3.8–5.0 in upper jaw length and 18.4–19.7 in HL; interorbital space narrow, its width 1.6–2.1 times eye diameter and 9.4–11.6 in HL; numerous papillae present on snout, interorbital space, temporal and lips, rather dense in holotype but scattered in paratype; anterior nostril tubular, extending downward; posterior nostril a hole covering by a compressed thin skin, its opening towards posteroventrally; upper lip with several fleshy thorn-shaped barbels (Fig. 4A), one between nostrils, very minute barbels along with the barbel in left side of holotype; and two posterior to posterior nostril (three in left side of paratype); rictus relatively short, behind posterior margin of eye; lower jaw short, distance from tip of snout to anterior end of lower jaw slightly longer than eye diameter; gill opening lateral, located at ventral half of body. Sensory pores small but conspicuous (Fig. 4B); supraorbital pores 1 (ethmoid)+3; infraorbital pores 3+3, 1 between nostrils, 2 below eye along upper jaw, and 3 behind eye in a vertical row; mandibular pores 5, the last pore slightly behind rictus; preopercular pores 2; interorbital pore 1; supratemporal pore 3 (single mid-temporal pore). Lateral line nearly completed, pores conspicuous, 0 pore before dorsal-fin origin, 8 anterior to gill opening, 118 anterior to anus and total 207 in holotype (0, 9, 114 and 195, respectively, in paratype), the last just before tip of tail about 1/3 HL. All teeth small, conical, and relatively pointed; teeth on maxilla in holotype arranged uniserial, in paratype partly biserial but generally uniserial (Figs. 4B, C); dentary teeth biserial; 5 intermaxillary teeth arranged as chevron; vomerine teeth biserial in holotype, mid-part of vomer partly triserial in paratype. Dorsal and anal fins very low, ending at near tip of tail, end of anal fin slightly behind that of dorsal fin; dorsalfin origin before middle of head, right behind the mid-temporal pore and before the first lateral-line pore; pectoral fin extremely minute, flap-like, located at anterior corner of gill opening, its length 13.1–20.4% HL and base height 26.2–44.1% HL. Color when fresh condition (after refrigeration; Fig. 3): body purplish pale brown, darker dorsally; head yellowish, snout and lower jaw deep, tip of snout yellowish brown; fins dusky white. Color in preserved condition: purplish and yellowish color faded. Body pale brown, darker dorsally; head slightly paler than body, in paratype tip of snout dark brown and pale dusky white band between tip of snout and eye; fins dusky white. Etymology. The specific name ryukyuensis is derived from the type locality. Distribution. Only known from the two specimens collected from shore of Okinawa-jima Island, Ryukyu Islands, Japan. Ecological note. The present specimens were collected as stranded specimens caused by the extremely low temperatures by a serous cold wave coming from the Arctic (Hibino et al. 2021). In the type locality, several species of Muraenidae, Ophichthidae, Apogonidae, Syganidae, etc., were also collected at the same time.

Bascanichthys Jordan & Davis, 1891 Bascanichthys Jordan & Davis, 1891:621 (type species: Caecula bascanium Jordan, 1884, by original designation)., Published as part of 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, pp. 103-113 in Zootaxa 5189 (1) on page 104, DOI: 10.11646/zootaxa.5189.1.12, http://zenodo.org/record/7119307, {"references":["Jordan, D. S. & Davis, B. M. (1891) A preliminary review of the apodal fishes or eels inhabiting the waters of America and Europe. United States Commission of Fish and Fisheries, Report of the Commissioner, 16, 581 - 677., pls. 73 - 80.","Jordan, D. S. (1884) List of fishes from Egmont Key, Florida, in the Museum of Yale College, with description of two new species. Proceedings of the Academy of Natural Sciences of Philadelphia, 36, 42 - 46."]}