Leucicorus lusciosus Garman, 1899

Schwarzhans, Werner W., Nielsen, Jørgen G. & Mundy, Bruce C., 2022, Revision of the circumglobal deep-sea genus Leucicorus (Teleostei, Ophidiidae) with two new species, Zootaxa 5100 (4), pp. 541-558 : 548

Leucicorus lusciosus Garman, 1899

Table 1 , Figs. 1D–E , 2A , 3J–K , 5

Leucicorus lusciosus Garman, 1899: 146 .

Leucicorus lusciosus: Grey 1956: 218 ; Nielsen 1975: 109.

Material examined ( 2 specimens, SL 225–245 mm and a radiograph of SIO 81–148 ) .

Holotype: MCZ 28680, 245 mm SL, male, eastern tropical Pacific , 14 ° 46’N, 98°40’W, R / V Albatross , st. 3415, beam trawl, 3436 m, 10 Apr. 1891. Non-types : ZMUC P 771814, 225 mm SL, female, off Peru, 17°42’S, 78°59’W, R / V Akademik Kurchatov , st. 271, Sigsbee trawl, 2710–3080 m, 20 Dec. 1968. Radiograph and otolith of SIO 81–148 , 251 + mm SL, female, Panama Basin, 5.175°N, 81°68’W, R / V Melville, 40’ otter trawl, PA 3, 3900–4000 m, 31 Mar. 1931.

Diagnosis. Dorsal-fin rays 110–114 and anal-fin rays 87–99; total vertebrae 68–69. Extensive squamation on opercle, preopercle and occiput; 35 to 40 transversal scale rows on trunk above beginning of anal fin. Otolith elongate (OL:OH = 1.65–1.75), with inner face more strongly convex than outer face.

Comparison. L. lusciosus is most similar to L. gerringerae , due to the extensive squamation on head; however, it differs from L. gerringerae by having more dorsal- (110–114 vs. 97) and anal-fin (96–99 vs. 73–80) rays, smaller scales on head (~ 1 mm vs 2.0– 2.5 mm) and more scale rows on trunk above anal-fin origin (35–40 vs. 24–25). It differs from both L. atlanticus and L. lentibus by the extensive head squamation and a high number of transversal scale rows above origin of anal fin.

Description. The principal meristic and morphometric characters are shown in Table 1 . Body elongate and compressed with tapering tail; head broad with dorsal profile straight except for a slight concavity above eyes; head bones thin and fragile. Anterior nostril placed midway between upper lip and posterior nostril and the larger posterior nostril close to orbit. Orbit equal in length of snout; lens poorly developed or absent. Opercular spine thin and pointed. Body fully scaled, head with scales on opercle, preopercle and occiput. Pelvic fins each with two tightly joined rays. Pectoral fins placed on midbody. Mouth terminal; upper jaw ends below posterior edge of orbit; supramaxilla well developed. Anterior gill arch with 9–10 long developed and eight knob-like rakers. 1–2 pseudobranchial filaments.

Otolith ( Fig 3J–K ). Large otoliths up to 11.4 mm in length with slender, droplet-like shape (OL:OH = 1.65– 1.75). Ventral rim shallow; dorsal rim higher, broadly rounded, with obtuse pre- to mediodorsal angle; anterior rim broadly rounded; posterior tip slightly tapering. Inner face convex, outer face flat to slightly convex; otolith height: thickness = 2.0–2.6. Sulcus straight, shallow, narrow, with single well-defined colliculum; otolith length: sulcus length = 1.80–1.9; sulcus length: height = 3.6–4.3. Sulcus not connected to anterior-dorsal rim. Ventral furrow well expressed, close to ventral otolith rim; indistinct dorsal depression.

Distribution ( Fig. 5 ). Known from three localities in the East Pacific Ocean. Caught in bottom trawls at 2710– 4000 meters. Leucicorus lusciosus is the only species in the genus caught at bathyal depth. Two sightings by ROV from the NOAA ship Okeanos Explorer campaign south of Hawaii and near the southern Line Islands may also belong to L. lusciosus (see below).

Figures

FIGURE 1. A) Leucicorus atlanticus Nielsen, 1975, holotype, ZMUC P771813, 154 mm SL, 19°00’N, 80°38’W. B) Leucicorus gerringerae n. sp., holotype, VIMS 42888, 235 mm SL, 23°20–22.5’ N, 68°23–29.4’ W. C) Leucicorus lentibus n. sp., holotype, ZMUC P771812, 170 mm SL, 20°01’N, 154°05’W. D) Leucicorus lusciosus Garman, 1899, ZMUC P771814, 225 mm SL, 17°42’S, 78°59’W. E) Leucicorus lusciosus Garman, 1899, radiograph of holotype, MCZ 28680, 245 mm SL, 14° 46’N, 98°40’W.

FIGURE 2. Head drawings (lateral and top): A) Leucicorus lusciosus Garman, 1899, ZMUC P771814, 225 mm SL, 17°42’S, 78°59’W. B) Leucicorus gerringerae n. sp., holotype, VIMS 42888, 235 mm SL, 23°20–22.5’ N, 68°23–29.4’ W. C) Leucicorus atlanticus Nielsen, 1975, holotype, ZMUC P771813, 154 mm SL, 19°00’N, 80°38’W. D) Leucicorus lentibus n. sp., holotype, ZMUC P771812, 170 mm SL, 20°01’N, 154°05W.

FIGURE 3. Otolith drawings: A–D) Leucicorus atlanticus Garman, 1899; A, holotype, ZMUC P771813 (A1 anterior view, A2 medial view, A3 dorsal view); B, ZMUC P77585 (B1 medial view, B2 dorsal view); C, VIMS 06857 (C1 medial view, C2 dorsal view); D, BMNH 2020.11.16.1 (D1 medial view, D2 dorsal view). E–F) Leucicorus gerringerae n. sp.; E, holotype, VIMS 42888 (E1 anterior view, E2 medial view, E3 dorsal view); F, MNRJ 52795 (medial view). G) Leucicorus lentibus n. sp., holotype, ZMUC P771812 (G1 anterior view, G2 medial view, G3 dorsal view). H–I) Leucicorus sp.; H, SMF 28854, 85 mm SL (H1 medial view, H2 dorsal view); I, SMF 28854, 75 mm SL (I1 medial view, I2 dorsal view). J–K) Leucicorus lusciosus Garman, 1899; J, SIO 81–148 (J1 anterior view, J2 medial view, J3 ventral view); K, ZMUC P771814, medial view.

FIGURE 5. Distribution map of Leucicorus species.