Paraliparis plicatus, Stein, 2012

Stein, David L., 2012, Snailfishes (Family Liparidae) of the Ross Sea, Antarctica, and Closely Adjacent Waters 3285, Zootaxa 3285, pp. 1-120 : 91-95

Paraliparis plicatus n. sp.

Figs. 65, 66

Holotype. NMNZ P.043689, female, 286 mm TL, 263 mm SL, 71°55.80' S, 173°18.08' E, NW edge of Mawson Bank, R / V Tangaroa, Stn. IPY / CAML TAN 0802 /144, 23 February 2008, 1431– 1658 m. NMNZ P.043689/1, cleared and stained right pectoral girdle.

Diagnosis. Chin pores closely paired with an anterior crescent-shaped tissue fold. Teeth uniserial in premaxilla except near symphysis, where irregularly bi-or tri-serial for 9–10 teeth; mandibular teeth uniserial, gradually smaller anteriorly. V 66, P 21, C 7. Radials 4 (3+1), unnotched; scapula with strong helve, coracoid with a narrow dorsal slit. HL 16% SL, upper jaw about 36, anus-anal fin origin 177, chin pore interspace 2–3% HL. Body color purplish.

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Paraliparis

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FIGURE

Description. Counts. V 66 (14+52), D 56, A 51, C 7, P 21 (15+3+3), radials 4 (3+1), pc 6?, pores 2–?–7–1. Ratios. HL 16.0, HW <14.6, sn 3.9, E 3.5, orbit 4.7, io 7.6, uj 5.8, go 2.5, bd 19.8, preD 31.4, preA 45.1, aAf 28.5, UPL 12.7, LPL 14.1. In % HL: HW <91.2, sn 24.2, E 22.1, orbit 29.2, io 47.5, uj 36.5, go 15.4, bd 124.0, preD 196.2, preA 281.7, sna 91.4, aAf 176.9, UPL 79.1, LPL 88.4, cp 2.4, LLD 28.0.

Head short and deep, dorsal profile rising steeply through flat interorbital region. Snout short. Nostrils with raised rim, larger than nasal pores; anterior to orbit by about 1/2 eye diameter, on a horizontal with lower margin of orbit. Mouth horizontal, inferior, oral cleft reaching below anterior margin of orbit. Teeth simple, sharp, canines, uniserial in both jaws except anteriorly. About 25 uniserial premaxillary teeth, another 9–10 irregularly bi- or triserial near symphysis. Mandibular teeth about 50, uniserial, becoming smaller anteriorly, extending distinctly farther posteriorly than premaxillary teeth. Symphyseal gap present in both jaws. Eye prominent, pupil very large, almost equal to eye diameter. Interorbital space about half head width. Gill opening completely above pectoral fin base and slightly anterior to it, extending to level of upper pectoral ray, less than1/6 head; a small opercular flap clearly developed, supported by dorsally curved opercle. Chin pores closely set, smaller than those more posterior, not in a shallow pit but with anterior skin fold, the distance separating them greater than one pore diameter. Suprabranchial pore single with raised rim, directly above postero-dorsal end of gill opening.

Pectoral fin short, upper lobe about 80% HL, its longest ray not reaching midpoint of abdominal cavity; lower lobe longer than upper but not as long as head. Uppermost ray on horizontal with middle of eye. Upper lobe rounded, of 15 rays; notch moderately deep, notch rays three, gradually shorter ventrally, poorly developed (rudimentary, unsegmented, filamentous); lower lobe of three rays, insertion of lowest ray below preopercle, reaching posteriorly just past tip of upper lobe or slightly farther. A wide gap less than 1/3 HL present between lower pectoral fin lobes. Right pectoral girdle with four (3+1) radials, R1 and R2 large, oval, about equal in size; R3 much smaller, R4 round, similar in size to R1 and R2 but much larger than R3. Notches and foramina absent. Scapular helve well developed, scapular blade larger and broader. Coracoid head slit dorsally, helve long, slender, basal notch absent.

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FIGURE

Body thick, deepest behind head. Dorsal fin insertion between vertebrae 9–10, anal fin insertion between vertebrae 14–15. Dorsal and anal fins deepest at about 4/5 of SL towards tail. Anus well behind bases of lower pectoral fin lobes, below middle of upper lobe base and below gill flap. Peritoneum visible through body wall. Pyloric caeca about six, short, digitate. Hypural complex fused, slit absent. Caudal fin of seven rays (3/4), auxiliary rays absent. SECM apparently not well developed. Skin thick, fibrous.

Color of body in alcohol purplish, head, distal part of upper pectoral fin lobes, and lower lobe rays brownish, anal region blackish-brown. Orobranchial cavity dusky-blackish. Peritoneum black, stomach and pyloric caeca pale.

Distribution. Known only from the type, collected between 1431–1658 m on the northwest edge of Mawson Bank.

Etymology. From the Latin plico, fold, indicating the skin fold in front of the chin pore pair.

Comparisons. Paraliparis plicatus is most similar to P. neelovi , but differs in having a chin pore fold (vs absent), four (vs three) radials, seven caudal rays (vs six), and many proportions slightly outside the range of variability for P. neelovi . It is also similar to P. longicaecus but differs in the chin fold (vs absent), shorter distance between chin pores (2 vs 4% HL), gill opening location (anterior to a vertical through pectoral fin base vs directly above), and shape (lobate shape vs a right angle), pectoral girdle structure (R1 and R3 and coracoid unnotched vs notched), longer anus-anal fin origin (177 vs 137% HL), shorter upper jaw length (36 vs 43% HL), and fewer vertebrae (66 vs 69). It could be confused with P. epacrognathus also, but differs notably in having three rudimentary but long pectoral notch rays (vs reduced to bases only), chin pore fold (vs absent), longer gill opening of about 15% HL (vs 11%), longer snout to anus distance of about 91% HL (vs 80%), and other differences.