Ophichthus microstictus, 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 : 28-31

Ophichthus microstictus sp. nov.

Figures 29–31 , Table 3

Holotype. MNHN 2001-0007, 445 mm, male, Tonga, Nkotu Group (19o52'29"S, 174o38'44"E), Sta. CH 1563, trawled in 362–388 m on 8 June 2000.

Paratypes. MNHN 2001-1095, 394 mm, an unripe male, Fiji, Lau Ridge (18o40'S, 178o30'W), Sta. CP 1501, captured by otter trawl in 350–357 m, 13 Mar. 1999. MNHN 2001-1096, 413 mm, Fiji, Lakeba (18o12'S, 178o37'E), Sta. CP 1505 #37, captured by otter trawl in 420–450 m during Mar. 1999; MNHN 2001- 1069, 3(357–391 mm), Tonga, N. Ha'apa Group (19o06'27"S, 174o18'11"E), Sta. CH 1596, trawled in 371–437 m on 14 June 2000; CAS 229179, 390 mm, collected with MNHN 2001-1069; MNHN 2001-1070, 2(443–489 mm), Tonga, Nkotu Group (19o52'29"S, 174o38'44"E), collected with the holotype.

Non-paratype. MNHN 1987-1246, 438 mm, New Caledonia, Balade (20o19'S, 164o30'E), captured (presumably trapped) in 200 m by Laboute during 1978.

Diagnosis. A moderately elongate species of Ophichthus , subgenus Coecilophis , with: tail 57–59% and head 11% of total length; dorsal-fin origin slightly ahead of pectoral-tips; pectoral fins moderately elongate, wedge-shaped, shorter than jaw; posterior nostril a hole in upper lip, covered by a flap; head pores minute, inconspicuous, SO 1+4, IO 4+2, POM 2-3+6; teeth small, conical and numerous, uniserial on vomer, mandible, and anterior and posterior portions of maxillary, which are irregularly biserial; coloration pale, slightly darker dorsally, irregular faint white patches beneath lateral midline, all fins pale. Mean vertebral formula 13/56/154, total vertebrae 151–156 (n=9).

Counts and measurements (in mm) of the holotype. Total length 445; head 48.1; trunk 138.9; tail 258; predorsal distance 63; pectoral-fin length 13.8; pectoral-fin base 4.5; body depth at gill openings ~16; body width at gill openings ~14.5; body depth at anus ~15; body width at anus ~12.5; snout 9.3; tip of snout to rictus 16.8; eye diameter 6.3; interorbital distance 5.8; gill-opening height 7.5; isthmus width 7.3. Vertebral formula 13/57/154.

Description. Body moderately elongate ( Figure 29 ), compressed in posterior tail region, depth at gill openings 24–33 in TL. Branchial basket slightly wider and deeper than body. Head and trunk 2.3–2.4 in TL; head 8.8–9.2 in TL, 2.6–2.9 in trunk. Snout moderate, conical when viewed from above. Snout not bisected on underside by a groove. Lower jaw slightly included, upper and lower lips meet when mouth is closed. Mouth moderately elongate, rictus about 1/3 eye length behind rear margin of eye. Eye large, 2.2–2.7 in upper jaw and 7.1–7.6 in head, its center well behind middle of upper jaw. Tube of anterior nostril short, barely reaching lower lip when deflected downward. Lip barbels absent. Posterior nostril a hole above upper lip, covered by an anterior flap that extends beneath edge of mouth; a short crease in lower lip at anterior edge of posterior nostril. Dorsal-fin origin slightly in advance of pectoral tips. Dorsal fin low, in a groove that deepens posteriorly. Anal fin higher. Median fins expanded before tail tip. Pectoral fins wedge-shaped, slightly less than jaw in length. Pectoral-fin base in upper half of gill opening. Posterior half of tail markedly tapered, its tip pointed.

Head pores ( Figure 30 ) small, inconspicuous. Single median interorbital and temporal pores. Supraorbital pores 1+4, infraorbital pores 4+2, lower jaw pores 6, preopercular pores 1–3 (typically 3).

Teeth ( Figure 31 ) mostly small, conical, slightly recurved. Intermaxillary with a rosette of 4 small teeth, then a gap, then 4 small teeth, followed by a short gap and a row of 13 smaller linear vomerine teeth. Maxillary dentition uniserial anteriorly and posteriorly, 27–30 teeth in a row, with a central inner row of 8–11 teeth. Mandibular teeth uniserial, 25–30 teeth in a linear row, similar in size to inner row of mandibular teeth, becoming smaller posteriorly.

Color in ethanol yellow-tan throughout, paler on chin and ventral trunk region. Irregular faint white patches occur beneath the lateral midline of the trunk in all specimens and does not appear to be an artifact of preservation. Tip of chin and snout smudged. Anterior nostrils pale. All fins pale. Peritoneum unpigmented.

Size. The largest known specimen is 489 mm, an unripe male.

Etymology. From the Greek mikros (small) and stiktos (punctures), in reference to its minute cephalic pores; to be treated as a noun in apposition.

Distribution. Known from Fiji and Tonga at depths from 362– 450 m. A single specimen from New Caledonia, captured in 200 m, may be this species.

Remarks. This new species is described on the basis of the holotype and eight paratypes, however three of the paratypes were so badly contorted that accurate measurements could not be taken. For that reason they were excluded from Table 3 . The single specimen (MNHN 1987-1246) trapped in 200 m off New Caledonia appears to be this species, however it differs slightly in certain characters and therefore was not made a paratype. (It had also been extensively dissected and much of its neurocranium and brain were removed, such that some of its cephalic characters are compromised.) It differs from the Fijian and Tongan specimens in its slightly shorter head length (10.4% TL vs. 10.9–11.3% TL) and more posterior dorsal-fin origin (above the 17th vertebra vs. 12th–15th). In all other characteristics it seems to be the new species.

The new species is most similar to those species of subgenus Coecilophis that possess wedge-shaped pectoral fins and an anterior dorsal-fin origin, viz. Ophichthus lentiginosus and O. ishiyamorum . They share, as well, uniserial lower jaw dentition, a pale rather than a darkened posterior anal-fin base, and usually have three preopercular pores. The new species differs from those species in having more vertebrae (151–156 vs. 140–142 in O. lentiginosus and 130–132 in O. ishiyamorum ). It further differs from O. ishiyamorum in having its eye nearly centered above the upper jaw, rather than nearly reaching the line of the rictus.

The cephalic pores of this species are minute and very difficult to discern. It appears that this species typically has three preopercular pores. The holotype possesses three on each side, whereas four paratypes have 3 left/3 right, one has 3/2, two have 2/2, and one has 1/2. The specimen from New Caledonia has 3/3. Such variation is not atypical among deepwater Ophichthus , particularly those with pores reduced in size and number. McCosker and Rosenblatt (1998:417) and McCosker (2009:79) noted that the eastern Pacific deepwater species O. tetratrema typically has four preopercular pores but some specimens had three or less.

Figures

FIGURE 29. Holotype of Ophichthus microstictus, MNHN 2001 - 0007, 445 mm, from Tonga.

FIGURE 30. Head of holotype of Ophichthus microstictus, MNHN 2001 - 0007, 445 mm.

FIGURE 31. Dentition of holotype of Ophichthus microstictus, MNHN 2001 - 0007, 445 mm.

Tables

TABLE 3. Counts and proportions (in thousandths) of the holotype and five paratypes of Ophichthus microstictus sp. nov. TL = total length. HL = head length. * N = 9

	Mean	Range
TL (mm)	---	389–464
HL/TL Head and trunk/TL	111 420	108–113 409–429
Trunk/TL	306	297–320
Tail/TL Depth at gill opening/TL	582 40	571–591 30–42
Dorsal-fin origin/TL	140	135–146
Pectoral-fin length/HL Upper jaw/HL	297 343	277–317 307–368
Snout/HL	195	184–203
Eye/HL Predorsal vertebrae*	138 13	131–141 12–15
Preanal vertebrae*	56	55–58
Total vertebrae*	154	151–156