Ophichthus aniptocheilos, E, John, 2010

E, John, 2010, Deepwater Indo-Pacific species of the snake-eel genus Ophichthus (Anguilliformes: Ophichthidae), with the description of nine new species, Zootaxa 2505, pp. 1-39 : 9-11

Ophichthus aniptocheilos sp. nov.

Figures 11–12

Holotype. MNHN 2001-1061, 142 mm, sex not apparent, from Tonga (21o40.65'S, 175o19.37'W), Field no. DW 1537, captured by Warren dredge, in 391–421 m on 5 Jun 2000.

Diagnosis. A moderately elongate species of Ophichthus , subgenus Coecilophis , with: tail 56%, head 10%, and depth at gill openings 3.5% of TL; dorsal-fin origin above pectoral-fin tips; pectoral fins moderate, elongate and lanceolate; posterior nostril in upper lip; head pores small, SO 1+4,IO 4+2, PO 2, mandibular pores 6; teeth slender, pointed, uniserial on vomer and mandible and biserial on maxillary; coloration brown dorsally and pale ventrally, head speckled, tail dark posteroventrally. Mean vertebral formula 16/59/140.

Counts and measurements of holotype (in mm). Total length 142; head 14.5; trunk 27.5; tail 82; predorsal distance 24.3; pectoral-fin length 7.6; pectoral-fin base ~1.2; body depth at gill openings ~5; body width at gill openings ~3.2; body depth at anus 3.8; body width at anus ~3; snout 2.9; tip of snout to rictus 6.2; eye diameter 2.3; interorbital distance 1.4; gill-opening height ~1.4; isthmus width ~1.5. Vertebral formula 16/ 59/140.

Description. Body moderately elongate ( Figure 11 ), compressed throughout, depth at gill openings 28 in TL. Branchial basket wider and deeper than body. Head and trunk short, 2.3 in TL; head 9.8 in TL, 1.9 in trunk. Snout moderately acute when viewed from above. Snout not bisected on underside by a groove. Lower jaw included, upper and lower lips meet when mouth is closed. Mouth moderately elongate, rictus about 0.7 eye lengths behind rear margin of eye. Eye 2.7 in upper jaw and 6.3 in head, its center slightly behind middle of upper jaw. Tube of anterior nostril laterally directed. Lips without barbels. Posterior nostril within a short tube barely above upper lip. Dorsal-fin origin slightly behind appressed tip of most elongate pectoral ray. Dorsal fin low, in a groove that deepens posteriorly for its entire length. Anal fin higher, in a groove similar to that of dorsal. Pectoral fins pointed, elongate, longer than jaw, the posterior-most ray an extended filament. Pectoral-fin base in upper half of gill opening.

Head pores ( Figure 12 ) small, inconspicuous. Single median interorbital and temporal pores. Supraorbital pores 1+4, infraorbital pores 4+2, lower jaw pores 6 (difficult to discern), preopercular pores 2. Lateral-line pores present but difficult to enumerate, 8 before gill opening.

Teeth mostly small, conical. (Dentition was not illustrated in order to avoid damage to the specimen.) Intermaxillary with a rosette of 3 small teeth, followed by a gap, then 3 irregular, larger erect pointed teeth, abutted by a nearly linear row of 13 teeth on the vomer, becoming smaller posteriorly. Maxillary dentition biserial. An inner row of about 8–10 slightly recurved teeth begins behind level of posterior nostril. An outer row of 22–24 smaller erect teeth commences at level of anterior margin of eye. Mandibular teeth small, close set, about 32–33 in a single row.

Color in ethanol brown on dorsal surface and flanks resulting from numerous fine brown punctations. Throat, chin anteromedial edge of anterior nostrils pale; head and mid-ventral chin region overlain with brown speckling, densest along edge of lips. Inside of mouth, lateral-line pores, and all fins and tail tip pale. Base of anal fin blackened posteriorly, extending about 1/2 HL before tail tip. Peritoneum pale, overlain with numerous dark punctations comparable in size to those of flanks.

Size. Known from a single apparently juvenile (gonads undeveloped) specimen.

Etymology. From the Greek aniptos (unwashed) and cheilos (lips), in reference to its facial coloration; to be treated as a noun in apposition.

Distribution. Known from the holotype, taken in 391–421 m from off Tonga.

Remarks. I am hesitant to describe this single small specimen as new, however it is so unique in several of its characteristics that I presume that the adult, when discovered, will be easily identifiable.

The new species is similar to other species of Ophichthus , subgenus Coecilophis , which also occupy deep sand and mud substrates. All possess small dentition, posterior nostrils along the lip (rather than opening into the mouth) and proceeded by a flap, two rather than three preopercular pores, a lanceolate pectoral fin, and a plain coloration, some with a dark smudge along the anal fin near the tail tip. Its closest relatives appear to be Ophichthus genie , described from 350–500 m specimens from New Caledonia and the Maldives ( McCosker 1999), O. kunaloa , a deepwater Hawaiian species ( McCosker 1979, 2002), and O. tomioi , described herein from specimens from the Seychelles, Fiji, the Philippines, and the Marquesas. Ophichthus genie is most similar in vertebral number (139–147 vs. 140) and proportions, but differs in having biserial rather than uniserial mandibular dentition, in lacking comparable head spotting, and in having a pale posterior anal-fin base. Ophichthus kunaloa is similar in coloration and proportions, but has biserial mandibular dentition and more vertebrae (180–185 vs. 140). Ophichthus tomioi is similar in proportions and appearance but has biserial mandibular dentition and more vertebrae (166–189 vs. 140).

Figures

FIGURE 11. Holotype of Ophichthus aniptocheilos, MNHN 2001 - 1061, 142 mm, from Tonga.

FIGURE 12. Head of holotype of Ophichthus aniptocheilos, MNHN 2001 - 1061, 142 mm.