Ophichthus rutidoderma

Ophichthus rutidoderma (Bleeker, 1852) Fig. 6, Tables 1, 2 English name: Olive Snake Eel Ophisurus rutidoderma Bleeker, 1852: 30 (type locality: Jakarta, Java, Indonesia); Günther 1870: 63 (as Ophichthys rhytidoderma, unjustified emendation). Ophisurus rutidodermatoides Bleeker, 1852: 31 (type locality: Jakarta, Java, Indonesia); Günther 1870: 62 (as Ophichthys rhytidodermatoides, unjustified emendation). Ophisurus lumbricoides Bleeker, 1852: 32 (type locality unknown). Ophisurus macclellandi Bleeker, 1852: 33 (type locality: Jakarta, Java, Indonesia). Type material. Holotype • BMNH 1867.11.28.226, 945 mm TL, Jakarta, Java, Indonesia (only vertebral examination). Other material examined. 10 specimens, 415–867 mm TL: BMNH 1867.11.28.278, 569 mm TL, Jakarta, Java, Indonesia (Bleeker specimen of O. maclellandi) • BMNH 1867.11.28.292, 610 mm TL, Jakarta, Java, Indonesia (holotype of O. rutidodermatoides; only vertebral examination) • BMNH 1867.11.28.300, 415 mm TL (holotype of Ophisurus lumbricoides; only vertebral examination), Jakarta, Java, Indonesia • KAUM–I.39446, 867 mm TL, off Tanjung Sepat, Selangor, Malaysia • KMNH VR 100624 –627, 4 specimens, 569–748 mm TL, purchased at Bagan Datuk, collected off mouth of Perak River, Perak, Malaysia • OIM-E.55787, 278 mm TL, C ần Gi ờ fishing grounded, H ồ Chí Minh city, 15–17 m, Vietnam • OIM-E.55832, 590 mm TL, Bình Đại food market (ca 10°11'15"N, 106°41'40"E), Bình Đại District, Bến Tre province, Vietnam • OIM-E.55833, 700 mm TL, Đồng Hòa, C ần Gi ờ District, H ồ Chí Minh City, Vietnam. Diagnosis. An elongate Ophichthus with the following combination of characters: body with numerous longitudinal wrinkles, more than five longitudinal wrinkles on posterior part of eye; head length 5.7–7.2 % TL; tail length 65.7–67.5 % TL; two protrusions along upper lip (rarely 1 on one side); dorsal-fin origin behind pectoral-fin tip by less than one pectoral-fin length; SO 1 + 3; POM 4–6 (usually 5) + 2; teeth on maxilla uniserial initially, becoming biserial posteriorly; vomerine and dentary teeth biserial anteriorly, uniserial posteriorly; body bicolored; dorsal fin dark with narrow margin entirely, anal fin pale except ending; total vertebrae 195–199, MVF 15-63 - 197 (n = 9). Distribution. Southern Vietnam, Java, Indonesia, and Malay Peninsula of Malaysia. It is a shallow water species, collected adjacent to a river mouth. Collecting depth is estimated to be 5–20 m in Vietnam and Malaysia. Remarks. Ophichthus rutidoderma has been recorded only from the South China Sea and western Australia; however, there are no detailed descriptions (usually only the name in list) except the original descriptions including several synonyms and a young specimen record by Vo et al. (2019) from Ho Chi Minh City, southern Vietnam. In Vo et al. (2019), the young Vietnamese specimen (278 mm TL) was reported as the first record from Vietnam, accompanied by a detailed morphological description. Although they described the specimen as having SO 1 + 4 and maxillary teeth arranged in a single row, the correct characteristics are SO 1 + 3 and a maxilla with primarily one row of teeth, except at the posterior end, whereas an additional row of four teeth is present. McCosker (2007) noted the vertebral information of several types, but he did not mention other characters. The record from Western Australia is based on the original description of Ophichthus derbyensis (holotype: 258 mm TL) by Whitley (1941). While its VF closely matches that of O. rutidoderma, the locality of O. derbyensis is significantly distant from the South China Sea. Moreover, O. derbyensis differs in dental morphology, with a completely single row of vomerine teeth (vs 2 anteriorly and 1 posteriorly in O. rutidoderma), and maxillary teeth that are biserial in the anterior-middle region but uniserial posteriorly (vs uniserial anteriorly and biserial posteriorly in O. rutidoderma). As such, we tentatively exclude O. derbyensis from synonymy with O. rutidoderma. Actually, O. rutidoderma appears to be a unique species restricted to the southwestern part of the South China Sea extending to the western coast of the Malay Peninsula. Future studies to determine the validity of O. derbyensis are required.