Ophichthus alleni, 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 : 6-9

Ophichthus alleni sp. nov.

Figures 8–10 , Table 1

Holotype. AMS I.36257-001, 674 mm, female, from off Newcastle, New South Wales, Australia, trawled between 33o01'S, 151o59'E and 33o03'S, 152o01'E in 118–121 m, Field no. K 94-220-08, aboard FRV Kapala by K. Graham, at 0 635 hrs on 0 9 Sept. 1994.

Paratypes. CAS 227496 (previously AMS I.34211-001), 760 mm, female, from off Newcastle, New South Wales, Australia, trawled between 33o01'S, 151o56'E and 33o01'S, 151o59'E in 115–121 m, aboard FRV Kapala by K. Graham, on 0 2 Mar. 1993; CSIRO H 1102-2, 574 mm, female, SE of Cairns (17o43'S, 146o49'E), Queensland, Australia, Field no. S00685 /53, lobster trawl in 200 m, 30 Nov. 1985.

Diagnosis. A stout species of Ophichthus , subgenus Coecilophis , with: tail 57% and head 12% of total length; dorsal-fin origin above pectoral-fin base; pectoral fins small, rounded; posterior nostril in upper lip, covered by a flap; head pores minute, numerous, SO 1+4, IO 4+3, POM 3+9-10; teeth small and pointed, none elongate, uniserial on mandible and posterior half of vomer, biserial on maxillary; coloration pale, slightly darker dorsally, median fins pale. Mean vertebral formula 11/52.5/132, total vertebrae 131–133 (n=3).

Counts and measurements (in mm) of the holotype. Total length 674; head 80; trunk 210; tail 384; predorsal distance 83; pectoral-fin length 18.0; pectoral-fin base 6.8; body depth at gill openings ~30; body width at gill openings ~28; body depth at anus ~30; body width at anus ~27.5; snout 14.8; tip of snout to rictus 26.1; eye diameter 7.2; interorbital distance 10.6; gill-opening height 8.3; isthmus width 19.7. Vertebral formula 10/52/131.

Description. Body stout ( Figure 8 ), compressed in tail region, depth at gill openings 21–23 in TL. Branchial basket wider and deeper than body. Head and trunk short, 2.3 in TL; head 8.4–8.5 in TL, 2.6–2.7 in trunk. Snout not elongate, rounded when viewed from above. Snout not bisected on underside by a groove. Jaws subequal, upper and lower lips meet when mouth is closed. Mouth not elongate, rictus about 1/2 eye length behind rear margin of eye. Eye 3.4–4.9 in upper jaw and 10–11 in head, its center well behind middle of upper jaw. Tube of anterior nostril short, hardly capable of being deflected forward. Lip barbels absent. Posterior nostril a hole above upper lip, completely covered by a flap that extends below edge of lip. Dorsalfin origin above pectoral fin, above or slightly behind pectoral base. Median fins low, in grooves that deepen posteriorly for their entire length. Pectoral fins rounded, not elongate, less than jaw in length. Pectoral-fin base in upper half of gill opening.

Head pores ( Figure 9 ) numerous, small and inconspicuous. Single median interorbital and temporal pores. Supraorbital pores 1+4, infraorbital pores 4+3, lower jaw pores 9–10 (the third slightly enlarged), preopercular pores 3. Numerous minute (approximately 1/2 cephalic pore diameter) surface sensory neuromasts along cheeks and nape. Lateral-line pores minute, very difficult to enumerate.

Teeth ( Figure 10 ) small and pointed, not close set, none elongate. Intermaxillary with a rosette of 7 small teeth, then 3 irregular pairs, followed by a nearly linear row of 13 small teeth on the vomer, becoming smaller posteriorly. Maxillary dentition biserial. An inner row of 8–11 teeth begins behind level of anterior nostril, flanked by an outer row of 25–27 teeth, becoming smaller and closer set posteriorly. Mandibular teeth in a single row of 27–29 teeth, becoming smaller posteriorly, flanked by a short anterior inner row of 4–5 teeth. Color in ethanol uniform tan, darker dorsally, without markings, paler ventrally in head and trunk regions. Throat, inside of mouth and median fins pale. Snout, anterior nostrils and nape darker like dorsal surface of trunk and tail. Pectoral fins tan. Anus within a gray-brown halo equal to diameter of orbit. Peritoneum pale. Size. Largest known specimen is 760 mm. All types are ovigerous females.

Etymology. I take pleasure in naming this new species alleni to honor Gerald R. Allen, in recognition of his numerous and diverse contributions to the knowledge of fishes of Australia and beyond.

Distribution. Known from Queensland and New South Wales, Australia, trawled and trapped between 115– 200 m.

Remarks. The new species is most similar to Ophichthus echeloides and O. urolophus . Among the species of the subgenus Coecilophis these three are stouter than most (body depth of O. alleni is 21-23 in TL, O. echeloides is 23.5 in TL, and O. urolophus is 21–25 in TL), have a dorsal-fin origin slightly behind the pectoral-fin base (slightly more so in O. urolophus ), rounded pectoral fins, fewer total vertebrae than most Coecilophis ( O. alleni has 131–133, O. echeloides 125, and O. urolophus 134–139), uniserial mandibular dentition, and three preopercular pores. The location and proportions of the eye and jaw to each other and to the head length are also very comparable. Ophichthus alleni and O. echeloides have biserial maxillary dentition, whereas that of O. urolophus is mostly uniserial.

Ophichthus alleni also differs from other Coecilophis in the degree of development of its free sensory neuromasts. Whereas other large shallower water ophichthines such as Ophisurus serpens (cf. Allis 1903: Figs. 1–8) have obvious arrays of papillae along their cheeks and nape, the development appears to be reduced in many of the species of the subgenus Coecilophis . The degree of development of free sensory neuromasts is probably related to the soft bottom habitats that they occupy ( McCosker 1977: 38). The apparent development of such neuromasts in O. alleni may also be related the large size of the specimens.

Figures

FIGURE 8. Holotype of Ophichthus alleni, AMS I. 36257 - 001, 674 mm, from Australia.

FIGURE 9. Head of holotype of Ophichthus alleni, AMS I. 36257 - 001, 674 mm.

FIGURE 10. Dentition of holotype of Ophichthus alleni, AMS I. 36257 - 001, 674 mm.

Tables

TABLE 1. Counts and proportions (in thousandths) of the holotype and two paratypes of Ophichthus alleni sp. nov. TL = total length. HL = head length.

	Mean	Range
TL (mm)	---	574–760
HL/TL	118	117–119
Head and trunk/TL	431	430–434
Tail/TL	569	566–570
Depth at gill opening/TL	45	44–46
Dorsal-fin origin/TL	132	123–138
Pectoral-fin length/HL	225	213–236
Upper jaw/HL	374	326–444
Snout/HL	187	173–204
Eye/HL	94	90–103
Predorsal vertebrae	11	10–12
Preanal vertebrae	52.5	52–53
Total vertebrae	132	131–133