Careproctus pellucicauda, Stein, David L., 2012

Stein, David L., 2012, A Review of the Snailfishes (Liparidae, Scorpaeniformes) of New Zealand, Including Descriptions of a New Genus and Sixteen New Species, Zootaxa 3588, pp. 1-54 : 13-15

Careproctus pellucicauda n. sp.

Figs. 9 , 10

Holotype. NMNZ P.038024, female, 126 mm SL, 145 mm TL, 46° 38.80' S, 178° 30.03' E, Bounty Trough, 10 October 2001, R/V Tangaroa, Stn. TAN 0 116, 2786– 2821m. NMNZ P.038024/1, cleared and stained right pectoral girdle.

Diagnosis. Vertebrae 53, pectoral fin rays 25, caudal fin rays 10. Teeth lanceolate, chin pores two, well separated; pectoral fin long, about 34% SL, slightly more than 150% HL, reaching beyond anal fin origin. Dorsalmost pectoral fin ray with large irregular triangular base extending ventrally to partially cover base of second ray. Pleural ribs absent. Posterior third of body unpigmented.

Description. Counts. V 53, D 47, A 40, C 10, P 25, radials ≥2, pc ≥ 6, pores?–?–?–1. Ratios. HL 22.1, HW <16.6, sn 5.2, E 6.2, orbit 7.1, io ~10.2, uj 12.0, go 11.3, UPL 34.1, LPL 18.6, md 9.4, disk 6.3, da 3.1, preD 27.9, preA 36.6, ma 18.7, aAf 16.0. In % HL: HW <74.9, sn 23.3, E 25.9, orbit 31.9, io 43.4, uj 54.1, go 50.9, UPL 154.1, LPL 84.2, md 42.6, disk 28.7, preD 126.2, preA 165.2, ma 84.6, aAf 72.4.

Head relatively small, profile rounded, its length slightly more than 1/5 SL, depth slightly greater than length. Snout short, almost vertical, its length about 1 1/2 times orbit, not projecting anterior to upper jaw. Nostrils single, on level with lower half of pupil. Eye large, prominent, about 1/4 HL, orbit slightly below dorsal profile of head but in lateral view not entering it; in dorsal view with skin shrunken, orbits forming a shallow depression in interorbital region. Interorbital space a little less than half HL. Mouth horizontal, terminal, upper jaw reaching to below posterior half of orbit. Lower jaw length equal to that of upper, not included. Teeth lanceolate in both jaws, forming bands consisting of about 30 oblique rows of up to five teeth each. Distinct symphyseal tooth gaps present in both upper and lower jaws. Gill opening unusually long, about 1/2 head length, extending above and ventrally in front of 8–9 pectoral fin rays. Opening extends above opercular flap and curves dorsally and then almost horizontally toward tail. Opercular flap acutely triangular, extending well beyond pectoral fin base, its dorsal edge supported by a blunt opercular spine, its lower margin unsupported. Circumoral pores large, many remaining pores damaged, pore formula impossible to determine; chin pore pair large, distinctly separated by a distance about equal to pore diameter, not in a pit. A single suprabranchial pore present on each side above opercle tip.

Pectoral fin clearly divided into upper and lower lobes. Uppermost pectoral fin ray well below orbit, even with posterior corner of upper jaw, its base consisting of a broad irregular triangular plate extending ventrally over dorsal part of second ray base. Base of second ray smaller, but relatively large compared to bases of rays 3–5, which are distinctly smaller and shorter. Bases of rays 6–14 much longer and stouter than rays 3–5 ( Fig. 9 C). Rays on right side 14+4+7. Upper fin lobe long, reaching posteriorly beyond anal fin origin to about 11th ray, notch deep, rudimentary rays absent; longest lower lobe ray reaching about 2/3 of distance to end of abdominal cavity, lowest (anteriormost) ray rudimentary, its base below corner of mouth. Rays in notch distinctly more widely spaced than those in upper and lower lobes. Right pectoral girdle damaged; radials at least 1+?+?+1, rounded, unnotched. Scapula strongly developed, broad based, its dorsal margin almost straight, deeply notched anteroventrally; coracoid stout, strongly webbed, triangular.

Body deepest at rear of head just above gill flap, tapering evenly and slowly to caudal fin. Disk small, egg-shaped, anterior part narrower than posterior, the margin of which is scalloped by protruding tips of supporting rays. Disk length slightly less than eye diameter, directly below orbit. Distance from posterior margin of disk to anus about half disk length. Predorsal length greater than head, preanal fin length about 1/3 SL. Vertebrae 11+42. First dorsal fin ray origin between vertebrae 5–6. Anterior dorsal fin rays somewhat shorter than those in mid-fin, no anterior rudimentary rays present. Anal fin origin between vertebrae 10–11. Pleural ribs absent. Hypural plate single, fused, slit absent. Principal caudal rays 1+4/5, a single dorsal procurrent ray present. Skin thin, easily damaged.

Fresh color completely black (head darker) except for posterior of tail, which is generally unpigmented. Color in alcohol: head and abdomen dark brown, body brown except for last 30 mm of tail, which does not appear to be skinned and is unpigmented. Disk white. Orobranchial cavity dusky; peritoneum black (visible through body wall), stomach and pyloric caeca pale.

Distribution. Known from a single specimen taken in the Bounty Trough near New Zealand at 2786–2821 meters depth.

Etymology. The specific epithet pellucicauda from the Latin pelluceo, transparent, and cauda, tail, referring to the unpigmented caudal region.

Comparisons. A member of the subgenus Careproctula . Careproctus pellucicauda is most similar to C. profundicola Duhamel 1992 in its general shape, color, number of vertebrae and rays of all fins, lengths of gill opening and pectoral fin, and color pattern (lacking pigment posteriorly). It differs in tooth size and shape (lanceolate vs smaller, conical), shape of opercular flap (distinctly lobate with opening extending well above and behind lobe vs quadrangular, gill opening not extending above and behind lobe), orbit diameter (32 vs 19% HL), shorter predorsal and preanal fin distances (28 and 37 vs 34 and 43 % SL respectively), lack of rudimentary pectoral fin rays (vs present in notch), and number of pyloric caeca (6 vs 12). In length of pectoral fin, head, and gill opening it is similar to C. longipectoralis Duhamel 1992 , but it differs distinctly in most other characters, notably vertebrae (53 vs 58), and pectoral rays (25 vs 27–28). It differs distinctly from C. novaezelandiae in many characters, most prominently pectoral fin rays (25 vs 37–38), caudal fin rays (10 vs 12), teeth (lanceolate vs trilobed), and gill opening (in front of 8–9 rays vs above fin).

The holotype has about ten ripe eggs up to 4.2 mm diameter.

Comments. The unusual structure and arrangement of the pectoral fin ray bases of C. pellucicauda may be unique in the family; normally, all pectoral fin ray bases are proportionally similar, depending on the diameter of the ray. The function of the enlarged bases of the first pectoral fin rays are unknown, but perhaps they tie the top few rays together to help them function as a unit.

The specimen appears to have been freezer burned prior to fixing; its tissues are stiff and difficult to manipulate. Its similarity in appearance and counts to C. profundicola from the Banzare Bank (much farther east and south than New Zealand) especially in color pattern, is striking.

Figures

FIGURE 9. Careproctus pellucicauda n. sp. Holotype. NMNZ P. 038024, 126 mm SL. A. lateral view; B. NMNZ P. 038024 / 1, right pectoral girdle; C. dorsal pectoral fin rays, showing enlarged ray bases.

FIGURE 10. Careproctus pellucicauda n. sp. Holotype. NMNZ P. 038024, 126 mm SL. Lateral view of fresh specimen. (Photo by R. McPhee, Te Papa)