Ophichthus humanni, 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 : 18-20

Ophichthus humanni sp. nov.

Figures 19–21

Holotype. MNHN 1997-0600, 669 mm, a male, from Vanuatu (15o08'S, 166o53'E), Campaigne Musorstom 8, 1994, Sta. CP 1119. captured by otter trawl in 254–300 m in Oct. 1994.

Diagnosis. An elongate species of Ophichthus , subgenus Coecilophis , with: tail 54% and head 8% of total length; dorsal-fin origin 3.5 pectoral-fin lengths behind head; pectoral fins rounded, not elongate; posterior nostril in upper lip, covered by a flap; head pores minute, SO 1+2, IO 4+2, POM 2+6; teeth pointed, stout, not numerous, irregularly biserial on vomer and maxillary, mostly uniserial on mandible; coloration uniform tan, pale ventrally, fins pale. Vertebral formula 19/70/168.

Counts and measurements (in mm) of the holotype. Total length 669; head 54; trunk 252; tail 363; predorsal distance 101; pectoral-fin length 13.4; pectoral-fin base 3.8; body depth at gill openings ~16.5; body width at gill openings ~15; body depth at anus ~16; body width at anus ~15; snout 10.7; tip of snout to rictus 20.4; eye diameter 5.0; interorbital distance 7.5; gill-opening height 6.2; isthmus width 7.5. Vertebral formula 19/70/168.

Description. Body elongate ( Figure 19 ), compressed in posterior tail region, depth at gill openings 40.5 in TL. Branchial basket wider and deeper than body. Head and trunk 2.2 in TL; head 12.3 in TL, 4.7 in trunk. Snout not produced, rounded when viewed from above. Snout not bisected on underside by a groove. Jaws subequal. Lips do not meet when mouth is closed. Mouth moderately elongate, rictus about 1.5 eye lengths behind rear margin of eye. Eye 4.1 in upper jaw and 11 in head, its center slightly behind middle of upper jaw. Tube of anterior nostril reaches middle of lower lip. A small rectangular patch between anterior and posterior nostrils, slightly slit in advance of posterior-nostril flap. Posterior nostril a hole above upper lip, entirely covered by a flap that extends well below edge of lip. Dorsal-fin origin far behind pectoral-fin tips, nearly a head length behind gill openings. Median fins low, lying in grooves. Pectoral fins rounded, not elongate, about 1.5 in jaw length. Pectoral-fin base in upper half of gill opening. Tail tip barely pointed, nearly blunt, slightly expanded dorsally and ventrally.

Head pores ( Figure 20 ) small, inconspicuous. Single median interorbital and temporal pores. Supraorbital pores 1+2 (posteriormost appears to be missing), infraorbital pores 4+2, lower jaw pores 6, preopercular pores 2. Lateral-line pores minute, difficult to enumerate.

Teeth ( Figure 21 ) stout, conical, pointed, slightly recurved. Intermaxillary with a rosette of 5 small teeth, then 3 irregular pairs of erect, larger vomerine teeth, followed by 11 irregular smaller teeth. Maxillary dentition biserial. An inner row of 12 pointed, slightly recurved teeth begins well ahead of level of orbit. An outer row of 15–17 more evenly-spaced teeth commences slightly ahead of anterior margin of eye. Mandibular teeth pointed, not close set, 3 irregular pairs anteriorly followed by 12–14 in a single row.

Color in ethanol uniform tan, ventral surface pale. A short dark smudge about 1/2 eye diameter present on posterior dorsal surface of tail (this smudge is much smaller and paler than that of those congeners with dark posterior anal-fin bases). All fins pale. Pectoral-fin base overlain with fine dark speckling forming a rectangular blotch. Snout and lips overlain with a diffuse minute speckling. Mandibular pores surrounded by minute speckling. Cheeks, throat, palate, and medial surface of anterior nostrils pale. Peritoneum pale ventrally, with a few fine dark speckles along dorsal surface.

Size. The holotype is a 669 mm male with mature gonads.

Etymology. Named in honor of Paul Humann, underwater photographer, author, and friend, who has generously aided ichthyologists with his photographs and observations.

Distribution. Known only from the holotype, from Vanuatu, captured in 254– 300 m.

Remarks. Although known only from the holotype, the specimen is in such excellent condition that an analysis of its relationships is possible. The new species possesses a unique amalgam of character states, several of which are possessed by other long-jawed species of the subgenus Coecilophis . In combination, however, those characters are possessed only by the new species. It differs in pectoral-fin shape from all those which possess an elongate filamentous pectoral fin ( O. tomioi , O. congroides , O. aniptocheilos , O. genie , O. kunaloa and O. mystacinus ) as well as those with a paddle-shaped pectoral fin ( O. alleni and O. hirritus ). It has two rather than three preopercular pores, a condition shared with O. alleni , O. echeloides , O. hirritus , O. ishiyamorum , O. megalops , O. hirritus , O. lentiginosus , O. megalops , and O. microstictus . It lacks the blackened posterior anal-fin base and its dorsal fin arises well behind the pectoral fin. Not only is it unique in this combination of character states, but it is also lacks two supraorbital pores (1+2 rather than 1+4), has fewer, more stout teeth, and possesses a small labial flap (its function unknown) between the anterior and posterior nostrils.

Figures

FIGURE 19. Holotype of Ophichthus humanni, MNHN 1997 - 0600, 669 mm, from Vanuatu.

FIGURE 20. Head of holotype of Ophichthus humanni, MNHN 1997 - 0600, 669 mm.

FIGURE 21. Dentition of holotype of Ophichthus humanni, MNHN 1997 - 0600, 669 mm.