Ophichthus, Ahl, 1789

Bogorodsky, Sergey V., Mal, Ahmad O. & Alpermann, Tilman J., 2020, Description of a new snake eel Ophichthus olivaceus (Teleostei: Anguilliformes Ophichthidae) from the Red Sea, Zootaxa 4750 (1), pp. 31-48 : 33-34

Key to selected Indian Ocean species of Ophichthus

This key is based primarily on McCosker (in press). Many western Pacific species of Ophichthus co-occur with Indian Ocean congeners, however, they are excluded here unless they are also known from the Indian Ocean; a worldwide revision of this large genus is needed. As well, several species are currently assigned to Pisodonophis or to Ophichthus and their status will also require a revision of those genera. In this key we cautiously treat Pisodonophis hijala ( Hamilton 1822) as a species of Ophichthus , recognizing that it may well be a species of Pisodonophis , and is a possible synonym of P. cancrivorus ( Richardson 1848) (see Talwar & Jhingran (1991) and Kottelat (2013)). Mc- Cosker reported (in press) that “The status of this species remains uncertain, as the type specimens are lost. Recently collected specimens from Myanmar (two from the Irrawaddy River) fit Hamilton’s original description.”

1a Body with one row of pale spots along lateral line ( India, shallow freshwater, brackish and marine)................................................................................................... O. hijala ( Hamilton 1822)

1b Body lacks a row of pale spots along lateral line............................................................. 2

2a Head and body pale, with dark saddles or with 2–3 rows of dark or ocellated spots; pectoral fins rounded, not elongate; jaw teeth uniserial............................................................................................ 3

2b Head and body coloration uniform, may be darker dorsally, but without spots or saddles; pectoral fins either rounded or attenuate and elongate; jaw teeth in one to three rows............................................................. 7

3a Head and body with numerous dark or ocellated spots, not appearing as saddles................................... 4

3b Body lacks spots, but head variously with spots and saddles.................................................... 5

4a Head and body with numerous ocellated spots, those on body in 2–3 regular, alternating rows of spots separated by wide pale interspaces (East Africa to Marquesas Islands).................................... O. polyophthalmus Bleeker 1864

4b Head and body with numerous dark spots, those on body in 2 irregular rows of large and small spots, largest spots about equal in size to interspaces (Red Sea and South Africa to Japan).......................... O. erabo ( Jordan & Snyder 1901)

5a Body with 18–27 prominent dark saddles or bars, including a conspicuous wide saddle above gill opening, anterior head with golden to orange spots (East Africa to the Society Islands)................................ O. bonaparti ( Kaup 1856)

5b Color not as described above........................................................................... .. 6

6a Head with an obvious broad brown or black saddle and two pale bands; trunk and tail uniformly brown ( Myanmar to the Society Islands)...................................................................... O. cephalozona Bleeker 1864

6b Dorsal surface of head and gill basket brownish black; dorsal surface of trunk and tail overlain with brown irregular blotches and saddles, ventral surface distinctly pale (India and Myanmar to Japan and Australia).................................................................................................. O. lithinus ( Jordan & Richardson 1908)

7a Body elongate to extremely elongate, its depth behind gill openings> 40 in TL..................................... 8

7b Body stout to moderately elongate, its depth behind gill openings <40 in TL.................................... .. 12

8a Dorsal-fin origin above or slightly behind pectoral-fin tip; tail length 1.4–1.6 in TL; teeth uniserial; vertebrae>220 ( India to Taiwan)..................................................................... .. O. macrochir ( Bleeker 1852)

8b Dorsal-fin origin distinctly behind pectoral-fin tip; tail length 1.6–1.8 in TL; teeth biserial or triserial; vertebrae <220...... 9

9a Body very elongate, depth at gill openings 53–90 in TL; vertebrae 206–214...................................... 10

9b Body moderately elongate, depth at gill openings 43–53 in TL; vertebrae 156–186................................ 11

10a Head length 6.5 in trunk length; maxillary teeth in 3 rows; vertebrae 214 ( India)............. O. microcephalus Day 1878

10b Head length 5.5–6.1 in trunk length; maxillary teeth in 2 rows anteriorly, in one row posteriorly; vertebrae 206–214 ( India)............................................................................ O. chilkensis Chaudhuri 1916 *

11a Dorsal-fin origin half a head length (1.5 pectoral-fin lengths) behind level of gill opening; teeth biserial anteriorly on lower jaw; vertebrae 174–186 (western Indian Ocean)........................................... O. marginatus ( Peters 1855)

11b Dorsal-fin origin more than a head length (3 pectoral-fin lengths) behind level of gill opening; teeth uniserial anteriorly on lower jaw, becoming biserial posteriorly; vertebrae 156–158 ( India)............................................................................................... O. johnmccoskeri Mohapatra, Ray, Mohanty & Mishra 2018

12a Head short, head length 14.5–16 in TL ( South Africa to Namibia)......................... ... O. serpentinus Seale 1917

12b Head moderately large, head length <12 in TL............................................................. 13

13a Dorsal-fin origin above or slightly in front of gill openings; dorsal fin greatly elevated; anterior part of dorsal fin, median fin margins and pectoral fins black (southern Taiwan to the Society Islands, and possibly from the Indian Ocean)........................................................................................... O. altipennis ( Kaup 1856)

13b Dorsal-fin origin above or behind pectoral-fin tips; dorsal fin low or only slightly elevated; pectoral fins and median fins (except near tail tip in some species) of larger specimens pale.................................................... 14

14a Dorsal-fin origin behind pectoral-fin tip by more than 3 pectoral-fin lengths..................................... 15

14b Dorsal-fin origin varying from above pectoral fin to behind pectoral-fin tip by less than 2 pectoral-fin lengths........... 17

15a Dorsal-fin origin two head lengths behind level of gill openings; tail length 2.0 in TL; body depth 23 in TL; vertebrae 153 ( Myanmar, depth 460 m)............................................... O. naga McCosker & Psomadakis 2018

15b Dorsal-fin origin about a head length behind level of gill openings; tail length 1.7–1.8 in TL; body depth 27–38 in TL; vertebrae 167–178........................................................................................... 16

16a Head length 11.0– 12.6 in TL; 3 preopercular pores; pectoral fins rounded; median fins pale ( Seychelles, depth 600 m).................................................................................... O. hirritus McCosker 2010

16b Head length 8.9–9.8 in TL; 2 preopercular pores; pectoral fins wedge-shaped; median fins pale, anal fin dark basally ( Madagascar, New Caledonia, and Vanuatu, depth 355–580 m)........................... O. brachynotopterus Karrer 1983

17a Teeth biserial in upper jaw and biserial or partly biserial in lower jaw........................................... 18

17b Teeth uniserial in jaws................................................................................ 22

18a Dorsal-fin origin behind pectoral-fin tip by about 1.5 pectoral-fin length; head moderately large, the length 7.1–7.7 in TL; teeth in lower jaw uniserial anteriorly, becoming biserial posteriorly and ending as triserial (Andaman Sea, depth 314–363 m)................................................ O. mccoskeri Sumod, Hibino, Manjabrayakath & Sanjeevan 2019

18b Dorsal-fin origin above pectoral fin; head moderate, the length 8.4–11.0 in TL; teeth in lower jaw entirely biserial or biserial anteriorly........................................................................................... 19

19a Two minute barbels present on upper lip; vomerine and lower jaw teeth in two rows anteriorly; dark gray-brown, paler ventrally, pectoral and median fins black ( Myanmar, depth 103 m).................... O. nansen McCosker & Psomadakis 2018

19b No barbels on upper lip; vomerine teeth in a single row, lower jaw teeth entirely in two rows; body and fins mostly pale... 20

20a Head length ~ 8.4 in TL; median fins pale posteriorly; 3 preopercular pores; pectoral fins rounded; vertebrae 125 (Red Sea, depth 300 m)................................................................ O. echeloides ( D’Ancona 1928)

20b Head length 9.9–11.0 in TL; 2 preopercular pores; pectoral fins attenuate (slender); vertebrae 139–189................ 21

21a Tail length 1.6–1.7 in TL; eyes moderate in size, 6.9–8.7 in head length; anal fin pale overall; vertebrae 139–147 ( Maldives and New Caledonia, depth 435–500 m)................................................... O. genie McCosker 1999

21b Tail length 1.7–1.8 in TL; eyes large, 5.4–6.6 in head length; anal fin mostly pale, but becoming black near tail tip; vertebrae 166–189 ( Seychelles to Marquesas Islands, depth 300–423 m)............................. O. tomioi McCosker 2010

22a Head large, its length 6.7–7.1 in TL; vertebrae 130–132 (Gulf of Aden, depth 258–400 m). O. ishiyamorum McCosker 2010

22b Head length 8.4–11.0 in TL; vertebrae 136–156........................................................... .. 23

23a Tail length slightly shorter than head and trunk, its length 2.2 in TL; vomerine teeth uniserial (Red Sea, depth 35–63 m).................................................................. O. olivaceus McCosker & Bogorodsky sp. nov.

23b Tail length longer than head and trunk, its length 1.6–1.9 in TL; vomerine teeth generally biserial.................... 24

24a Vertebrae 150–161; head coloration uniform ( India, Taiwan, Japan)......... O. machidai McCosker, Ide & Endo 2012 **

24b Vertebrae 136–141; snout and lower jaw blackish (East Africa to the Philippines)................................................................................................... O. apicalis (Anonymous [Bennett] 1830)***