Ophichthus macrochir ( Bleeker, 1852 )

Ophichthus macrochir ( Bleeker, 1852) View in CoL

Fig. 5 View Figure 5 , Tables 1 View Table 1 , 2 English name: Bigfin Snake Eel Chinese name: 大鰭蛇鰻 View Table 2

Ophisurus macrochir Bleeker, 1852: 26 (type locality: Jakarta, Java, Indonesia). View in CoL

Ophisurus woosuitingi Chen, 1929: 22, pl. 2 (type locality: Ying Khou, Kwangtung, China).

Material examined.

Eight specimens, 324–824 mm TL: BMNH 1867.11.28.262 (Bleeker specimen), 501 mm TL, Jakarta, Java, Indonesia ; CAS 52580, 324 mm TL, Dumaguete , Negros, Philippines • CAS 233838, 631 mm TL, Lagoon of Apulit Island , northern Palawan, Philippines • KMNH VR 100261 , 659 mm TL, Dong-gang , Taiwan • NMMB-P 23577 , 646 mm TL, Ke-tzu-liao , Kaohsiung, Taiwan • NMMB-P 24692 , 356 mm TL, Dong-gang , Taiwan • NMMB-P 36831 , 626 mm TL, Ke-tzu-liao , Kaohsiung, Taiwan • OIM-E.55830 , 544 mm TL, K ỳ Hà market (ca 15°28'20"N, 108°41'01"E), Tam Kỳ , Quảng Nam, Vietnam GoogleMaps ; OIM-E.558331 , ~ 824 mm TL (tail is broken), Đồng Hòa , Cần Giờ, Hồ Chí Minh city, Vietnam .

Diagnosis.

An elongate Ophichthus with the following combination of characters: body strongly wrinkled; head length 5.0–6.7 % TL; tail length 62.5–69.3 % TL; two protrusions along upper lip; dorsal-fin origin at approximately same vertical through pectoral-fin tip; SO 1 + 4, POM 4–5 (usually 5) + 2; teeth on maxilla mostly uniserial, on mandible biserial; teeth on vomer bi- or triserial; body uniformly black to dark brown; dorsal and anal fins dark gray to black; total vertebrae 214–221, MVF 11-70 - 217.

Distribution.

Thailand (Gulf of Thailand), Indonesia (Java and Sumatra), Vietnam, Philippines, southern China, Taiwan, and Japan (larva only in Japan). Usually occurring in shallow water above 25 m, but specimens from Taiwan were possibly collected deeper than 100 m.

Remarks.

We have not examined the holotype ( RMNH.PISC.7174 ) directly; however, McCosker (2022) noted the MVF of that holotype O. macrochir is 11 / 70 / 221, the only available data for the holotype. McCosker and Ho (2015) provided the range of the total number of vertebrae of the species as 207–218 in the key based on specimens collected from Taiwan. Ophichthus macrochir has been recorded from several regions with morphological information (cf. Allen and Erdmann 2012; Hibino 2019; McCosker 2022), but diagnostic characters were uncertain. In addition, some elongate species have been described or redescribed as valid species in recent years (e. g., Mishra et al. 2019; this study). Based on only our examination and vertebral information of the holotype, a new diagnosis is provided herein.

Ophisurus woosuitingi Chen, 1929 was originally described based on a single specimen collected from Kwangtung, southern China. We could not access the holotype of O. woosuitingi , but the description includes detailed information on its morphological features, with good illustrations of the head and anterior trunk. According to Chen (1929), the species has the following morphological features: strongly wrinkled body; head 6.0 % TL; body depth 1.4 % TL (70.8 in TL); eye 6.2 % HL; snout 18.7 % HL; pectoral-fin length ~ 20 % HL; dorsal-fin origin slightly behind the tip of the pectoral fin; SO? 1 (ethmoid not obvious) + 4, POM 5 + 2; preanal lateral-line pores 68; teeth on maxilla mostly uniserial, on mandible biserial; teeth on vomer bi- or triserial; body color uniformly blackish. It is evident that O. woosuitingi is a junior synonym of O. macrochir , although Tang and Zhang (2004) considered this name to be valid and separated it from O. macrochir .

Based on our extensive examination of O. macrochir , including specimens from various localities in the northwestern Pacific, we were unable to differentiate it from the Indian species O. chilkensis based on the counts and measurements except for the protrusions on the upper lip (1 vs 2; Table 2 View Table 2 ). According to the redescription by Mishra et al. (2019), differences in fin coloration can distinguish O. chilkensis from O. macrochir (dark gray to black vs dull white with posterior 1 / 3 of anal fin dark). Our investigation shows that the distribution of O. macrochir is restricted to the western Pacific, and the Indian records of O. macrochir might have been misidentifications of O. chilkensis .