Ophichthus shaoi McCosker & Ho

Ho, Hsuan-Ching, 2015, New species of the snake eels Echelus and Ophichthus (Anguilliformes: Ophichthidae) from Taiwan, Zootaxa 4060 (1), pp. 71-85 : 80-83

Ophichthus shaoi McCosker & Ho , sp. nov.

Long bodied snake eel

( Figs. 7–9 ; Table 3)

Holotype. NMMB-P 12228 (615 mm), Da-xi fish market, Yilan, NE Taiwan, bottom trawl, ca. 200 m, 22 Jan. 2010, coll. H.-C. Ho.

Paratypes. 12 specimens, 433–623 mm TL. Collected from Dong-gang fish market, Pingtung, SW Taiwan, bottom trawl, ca. 200 m: NMMB-P 2894 (565 mm), 100 m, 8 Nov. 2001; NMMB-P 11147 (480 mm), 30 Oct. 2010; NMMB-P 13656 (525 mm), 2 Jun. 2011; NMMB-P 13843 (623 mm), 5 Oct. 2010; CAS 237404 (623 mm), collected with NMMB-P 12843; NMMB-P 14079 (ex. NMMB-P 13656, 514 mm), 2 Jul. 2012; NMMB-P 14080 (ex. NMMB-P 13682, 433 mm), 2 Jul. 2012; NMMB-P 18019 (571 mm), no date; NMMB-P 22182 (ex. NMMB- P 12228, 617 mm), collected with the holotype; CAS 237403 (formerly NMMB-P 15525, 596 mm), 10 Nov. 2011; CAS 237383 (556 mm), 25 Dec. 2007. Collected from Ke-tzu-liao, Kaohsiung, SW Taiwan: NMMB-P 17850 (586 mm), 20 Aug. 2012.

Diagnosis. A moderately elongate species of Ophichthus with: tail 50–52%, head 9–10%, and body depth at gill opening 2.6–3.2% of total length; dorsal-fin origin above mid-pectoral fin; pectoral fin wedge-shaped, not elongate and well-developed; posterior nostril a hole within upper lip opening into mouth, not visible externally; a conspicuous upper lip barbel behind anterior nostril; pores small but conspicuous, SO 1+4, IO 6+2, POM 6+3; teeth small and conical, uniserial on jaws and mandible; coloration uniform grayish-brown, throat and ventral trunk region gray, body and tail brown, fins pale; total vertebrae 155–164, mean vertebral formula 11-69-159.

Counts and measurements of the holotype (in mm). Total length 615; head 55.8; trunk 239.2; tail 320; predorsal distance 67.3; pectoral-fin length 11.8; pectoral-fin base 3.3; body depth ca. 19 at gill openings; body width ca. 18 at gill openings; body depth at anus ca. 19; body width at anus ca. 17; body depth at branchial basket ca. 22.5; snout 12.0; tip of snout to rictus 16.7; snout overhang beyond tip of lower jaw 4.1; eye diameter 5.7; interorbital width 8.7; gill opening height 6.0; isthmus width 12.7. Left lateral-line pores 70; total pores 146. Vertebral formula 12-68-155.

Description. Body moderately elongate ( Fig. 7 ), subcircular to posterior tail region, then becoming more compressed, its depth at gill openings 26–30 in TL. Branchial basket slightly expanded. Head 3.9–4.4 in trunk. Head and trunk 2.0–2.1 and head 10.1–11.1 in TL. Snout pointed, moderately acute when viewed from above; underside of snout bisected by a v-shaped groove that extends nearly to base of anterior nostrils. Lower jaw included, its tip nearly reaching to posterior edge of anterior nostril tube. Upper jaw moderately elongated, rictus below a vertical from posterior margin of eye. Eye moderate, its center in posterior fifth of upper jaw, 2.5–3.6 in upper jaw and 8.1–11.2 in head. Anterior nostrils tubular, extending ventrolaterally from snout at ca. 45o, reaching tip of chin when directed downward. Posterior nostril a hole within upper lip and opening into mouth, not visible externally. Two down-pointing barbels along upper lip, the first prominent, behind base of anterior nostril by length of nostril base, the second, smaller, beneath anterior margin of orbit. Dorsal-fin origin begins behind middle of pectoral fin. Median fins low but obvious, lying within a groove, ending approximately an eye diameter before pointed tail tip. Pectoral fins wedge-shaped, not elongate and lanceolate, the longest rays slightly above mid fin.

Holotype Paratypes

TL (mm) 615 485–623 (n=9)

mean range HL/TL 91 94 90–99 Head and trunk/TL 489 489 477–496 Head pores apparent ( Fig. 8 ). Single median interorbital and temporal pores. Supraorbital pores 1+4, infraorbital pores 4+2 (labial pores 2–3 separated by a wide gap), lower jaw pores 6, preopercular pores 3, supratemporal pores 3. Faint rows of minute sensory papillae along the nape. Lateral-line pores faint but apparent; 9–11 before gill opening in an arching sequence, 11–14 before dorsal-fin origin, 69–72 before anus, 145–149 total, the last about a jaw length before tail tip.

Teeth ( Fig. 9 ) small, conical, slightly retrorse, uniserial and fairly closely spaced. An intermaxillary rosette of 7 teeth (the largest) followed by a uniserial pair followed by a gap and 14 uniserial vomerine teeth which decrease slightly in size posteriorly. Maxillary teeth ca. 16–18. Mandibular teeth 28–30, slightly larger anteriorly, a gap at the symphysis.

Coloration when fresh ( Fig. 7 ) uniformly brownish with head and belly paler. Median fins light brown becoming deep brown about a jaw length before tail tip. Pectoral fin grayish brown. Coloration lacks any notable markings. In preservative uniform gray on head and belly, becoming brown dorsally in trunk behind dorsal-fin origin, becoming uniform brown dorsally in trunk and throughout tail. Median fins white becoming gray/brown about a jaw length before tail tip. Pectoral fin pale gray like head, the upper rays dusky. Snout, anterior nostrils, and tail tip pale. Palate dusky. Peritoneum pale with slight speckling dorsally.

Size. The largest known specimen is 623 mm TL.

Etymology. We are pleased to name this new species in honor of Dr. Kwang-Tsao Shao of the Biodiversity Research Center, Academia Sinica, Taiwan.

Distribution. Known from the type series, collected from ca. 200 m depth, northeastern Taiwan off Da-xi fishing port and southwestern Taiwan off Dong-gang and off Ke-tzu-liao fishing ports.

Remarks. This new species is most similar to its congeners which possess: small, conical, uniserial dentition; moderately elongated and rounded bodies; the dorsal fin arising above the pectoral fin; wedge-shaped pectoral fins that are neither elongate nor filliform; a pointed conical snout that is split on its underside; two small snout barbels; a posterior eye location; and a nearly uniform body coloration. On that basis it appears to be most similar to Ophichthus machidai McCosker, Ide & Endo, 2012 , which differs from O. shaoi by having more predorsal and fewer preanal vertebrae (MVF 16-58-158 vs. 12-69-160), a slightly more posterior dorsal-fin origin, two rather than three preopercular pores, and slightly biserial vomerine dentition. Ophichthus shaoi appears similar to O. obtusus McCosker, Ide & Endo, 2012 which differs from O. shaoi in having fewer total vertebrae (148–153 vs. 155–164) and fewer preanal vertebrae (MVF 12-55-151 vs. 11-69-159), having black vs. pale median fins, and a shorter snout (14–21% of head length vs. 21–28% of head length). Ophichthus shaoi also appears to be similar to O. apicalis ( Bennett, 1830) which differs from O. shaoi by having fewer total (141–146 vs. 155–164) and fewer preanal vertebrae (MVF 13-51-144 vs. 11-69-159), a longer tail (62–63% of TL vs. 51–52% of TL), and a shorter snout (20–22% of head length vs. 21–28% of head length). Ophichthus shaoi differs in appearance from all of its Taiwanese congeners in its brown dorsal body coloration, which is subtly different in appearance than that of its grayish relatives. Ophichthus shaoi might also be mistaken for O. urolophus ¸ another SE Asian trawl and trapcaught ophichthid, which is similar in appearance and proportions, but differs in its dorsal-fin origin (above midpectoral fin vs. slightly behind), its slightly more slender body depth (26–31 vs. 21–25 in TL), its total vertebrae (155–164 vs. 134–139), and in its body coloration (pale orange vs. uniformly brown when fresh, and brown dorsally and throughout tail vs. pale ventrally and pale-brown dorsally when preserved).

Figures

FIGURE 7. Ophichthus shaoi McCosker & Ho, sp. nov. A. NMMB-P 12228, holotype, 615 mm TL. B – C. NMMB-P 17850, paratype, 586 mm TL. Bars indicate the origins of the dorsal fin (left) and anal fin (right).

FIGURE 8. Semi-diagrammatic illustration of lateral head of Ophichthus shaoi McCosker & Ho, sp. nov., from the holotype. Arrows point to the frontal pore (left) and median pore of supratemporal series (right).

FIGURE 9. Semi-diagrammatic illustration of dentition of Ophichthus shaoi McCosker & Ho, sp. nov., from the holotype. A. Upper Jaw. B. Lower Jaw.