Careproctus longibarbatus, Kai & Matsuzaki & Mori & Pitruk & Misawa & Tashiro, 2024

Kai, Yoshiaki, Matsuzaki, Koji, Mori, Toshiaki, Pitruk, Dmitry L., Misawa, Ryo & Tashiro, Fumihito, 2024, Snailfishes of the genus Careproctus (Perciformes: Liparidae) with a reduced pelvic disk: three new species and new records from the western North Pacific with comments on their phenotypic diversity, Zootaxa 5492 (2), pp. 191-213 : 197-201

Careproctus longibarbatus sp. nov. Kai, Pitruk & Tashiro

Japanese name: Hige-bikunin

Figs. 2C , 4 ; Table 1

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Careproctus mederi (not of Schmidt 1916): Kido 1988: 206; fig. 42 (description; southern Sea of Okhotsk); Nakabo and Kai 2013: 1212 (key and short description, in part; Sea of Okhotsk); Amaoka et al. 2020: 376, pl. 566 (photo and short description; Sea of Okhotsk).

Holotype. HUMZ 77646 , 230.0 mm SL, female, 44.800ºN, 144.433ºE, 800 m depth, 21 Sep. 1978, coll. by K. Kido.

Paratypes. HUMZ 77690, 214.6 mm SL, male, 41.617ºN, 144.333ºE, 980–1,020 m depth, 23 Sep. 1978 , coll. by K. Kido; HUMZ 78897, 224.8 mm SL, 44.792ºN, 144.442ºE, depth unknown, 20 Sep. 1978 , coll. by K. Kido; HUMZ 124178, 216.8 mm SL, female, 44.777ºN, 144.370ºE, 389 m depth, 15 Jul. 1992 ; HUMZ 121570 , 121571 , 175.6 – 218.6 mm SL, 2 females, 44.153ºN, 144.568ºE, 535 m depth, 22 Sep. 1991 ; HUMZ 126266, 201.1 mm SL, female, 44.143ºN, 144.7950E, 560 m depth, 29 May 1993 ; HUMZ 126328–126330 , 104.4 – 140.1 mm SL, 3 males, 45.067ºN, 144.152ºE, 439 m depth, 16 Jun. 1993 ; HUMZ 126457 , 203.0 mm SL, female, 45.087ºN, 144.318ºE, 652 m depth, 13 Jun. 1993 ; HUMZ 143331 , 217.0 mm SL, male, off Shari , Hokkaido, Japan, depth unknown, 22 Nov. 1995 ; HUMZ 196168 , 196170 , 207.2 – 207.4 mm SL, females, 44.521ºN, 141.131ºE, 237–241 m depth, 22 Apr. 2006 ; HUMZ 203646, 194.7 mm SL, male, off Rausu , Hokkaido, Japan, 356 m depth, 15 Sep. 2007, coll. K. Machi and T. Nobetsu ; FAKU 148477 (ex. HUMZ 196166 ), 223.0 mm SL, female, 44.521ºN, 141.131ºE, 237–241 m depth ; FAKU 149862, 203.3 mm SL, female, southern Sea of Okhotsk (no further data) .

Diagnosis. A species of Careproctus with the following combination of characters: vertebrae 61–66; dorsal-fin rays 56–60; anal-fin rays 50–54; pectoral-fin rays 28–34; pectoral fin with distinct (deep) notch, lower lobe moderately elongate, slightly shorter than upper lobe, extending to below gill opening; pelvic disk rounded, greatly reduced; cephalic pores 2-6-7-2, chin pores paired in separate pits; gill slit large, extending ventrally to pectoral-fin rays 12–19; teeth simple or slightly shouldered; anus located below posterior rim of orbit; peritoneum dark brown, stomach black.

Description. Measurements shown in Table 1 . Paratype data given in parentheses if different from holotype.

Body moderately deep, compressed, tapering posteriorly ( Fig.4 ). Skin thin, prickles absent or deciduous if present; gelatinous tissue under skin not developed. Head robust, moderately compressed, dorsal profile gradually sloping from nape to snout. Snout rounded, not protruding anterior to mouth. Mouth large, subterminal, slightly oblique; maxilla extending to mid orbit (or posterior rim of orbit); oral cleft extending to anterior rim of orbit. Premaxillary teeth simple or weakly shouldered, arranged in oblique rows of 8 (5–8) teeth per row forming broad band; inner teeth larger, recurved. Mandibular teeth simple or weakly shouldered, arranged in oblique rows of 6 (4–7) teeth per row forming broad band; inner teeth larger, recurved. Narrow diastema at symphysis of upper and lower jaws, upper diastema slightly wider. Orbit of moderate size, rounded; pupil rounded. Nostril single, with rim raised, at level with middle (middle to upper part) of orbit. Cephalic sensory pores of moderate size, rims thickened: nasal pores 2, maxillary pores 6, preoperculomandibular pores 7, suprabranchial pores 2; cephalic pore pattern 2- 6-7-2. Chin pores paired in separate pits, well separated. Coronal pore absent. Gill slit large, upper margin level with mid-orbit (or upper rim of orbit), extending ventrally to pectoral-fin ray 18 (12–19). Gill rakers 10, short, with tiny spines on tips (in FAKU 148477). Opercular flap rounded; tip level with anterior point of upper jaw. Pyloric caeca damaged in holotype (16–25), thick and long, covering two-thirds of stomach, on center-left side of visceral cavity.

Vertebrae 62 (61–66), precaudal 10 (9 or 10) and caudal 52 (51–56). Pleural ribs in 2 pairs (rarely 3), on abdominal vertebrae 9 and 10 (8–10). Dorsal-fin rays 58 (56–60), not exserted.Anteriormost dorsal-fin pterygiophore inserted between neural spines 3 and 4; anteriormost 2 (1 or 2) pterygiophore rayless. Anal-fin rays 51 (50–54), not exserted. One (1 or 2) anal-fin pterygiophores anterior to 1 st haemal spine, each bearing a single ray. Membrane of posterior dorsal- and anal-fin rays attached about equidistant to caudal fin. Caudal fin slightly rounded. Principal caudal-fin rays 9 (8–9), 4 and 4–5 rays on upper and lower hypurals, respectively; dorsal procurrent rays 0 (0–1), ventral procurrent rays 0 (0–1). Hypural plates fused with terminal vertebral centrum and parhypural, upper and lower hypural plate separated by narrow slit.

Pectoral fin deeply notched, with 34 (28–34) rays; upper lobe with 25 (20–25) rays, just reaching (or slightly beyond) level of anal fin origin; lower lobe moderately elongate, with 9 (7–9) rays, 5 th (4 th –5 th) ray from ventralmost longest, slightly shorter than upper lobe, extending to below gill opening. Rays in notch more widely spaced than rays of lobes. Tip of pectoral-fin rays of upper lobe slightly protruding, rays of lower lobe strongly exserted. Uppermost pectoral-fin base below level of ventral rim of orbit, level with tip of lower jaw. Lowermost pectoral-fin base below (below or slightly anterior to) anterior rim of orbit. Pelvic disk rounded, greatly reduced ( Fig. 4C–D ). Anus much closer to pelvic disk than to anal fin origin, located below posterior rim of orbit.

Pectoral girdle (based on FAKU 148477: Fig. 2C ): Lower part of pectoral girdle supported by sternohyoideus and pharyngoclavicularis externus. Proximal pectoral radials 4; radials 1–3 notched, hour-glass shaped, equally spaced, radial 4 rounded squarish, widely separated from radial 3. Interradial fenestrae 4, extending between scapula and radials 1–4; fenestrae 1–3 deformed diamond-shaped, fenestra 4 elliptical. Scapula broadly Y-shaped, with robust helve. Coracoid diamond-shaped, with short thin helve. Distal radials present at base of pectoral-fin rays 2–28.

Coloration ( Fig. 4 ): When fresh (based on HUMZ 124178), head and body pale pink; belly and chin whitish. Iris dark silvery. Dorsal, anal, caudal, and pectoral fins pale reddish; distal margins of posterior dorsal and anal fins partly darkish; upper margin of pectoral fin red. Pelvic disk white. When preserved, head, body, and fins white. Eyes black. Oral and branchial cavities pale; peritoneum dark brown; stomach black.

Reproduction. The holotype (230.0 mm SL) was an immature female with a short ovipositor (ca. 5 mm in length). The ovary was whitish, with small rounded eggs 0.61–0.89 mm in diameter. FAKU 148477 (223.0 mm SL) was a spent female with yolked (4.19–4.76 mm diameter) and small immature (less than 0.50 mm diameter) eggs. Yolked eggs rounded.

Distribution. Known only from the southern Sea of Okhotsk off Hokkaido, Japan, at depths of 202–1,020 m ( Kido 1988; present study) ( Fig. 3 ).

Etymology. The specific name “ longibarbatus ”, derived from Latin “longus” (long) and “barba” (barbel), refers to the relatively long barbel-like lower lobe of the pectoral fin.

Remarks. Kido (1988) described C. mederi from the southern Sea of Okhotsk as the first records from Japanese waters. However, as he noted, Kido’s (1988) specimens had higher numbers of vertebrae, and dorsal- and anal-fin rays than those given in the original description by Schmidt (1916). The present specimens of C. longibarbatus sp. nov., including Kido’s (1988) C. mederi , are readily distinguished from the syntypes and additional specimens of C. mederi (see description below) based on the following counts (vertebrae: 61–66 vs. 57–63; dorsal-fin rays: 56–60 vs. 52–56; anal-fin rays 50–54 vs. 47–52), as well as the length of the pectoral fin lower lobe (extending past anus vs. not reaching to anus; Tables 1 , 2 ), status of lower part of pectoral girdle (not protruding anteroventrally below mandible vs. protruding), and color of the peritoneum (dark vs. pale with black dots). In addition, yolked eggs of C. longibarbatus sp. nov. were rounded, whereas those of C. mederi are elliptical (see Description of C. mederi ). Among the species of Careproctus with a reduced disk, C. longibarbatus sp. nov. can be diagnosed as having the highest numbers of vertebrae, and dorsal- and anal-fin rays ( Tables 1 , 2 ).

Within the C. gilberti species group, C. parvidiscus is most similar to C. longibarbatus sp. nov. in having a moderately long pectoral fin lower lobe, extending to below the gill opening ( Imamura & Nobetsu 2002; this study). However, the former differs from the new species in having a smaller gill slit, extending ventrally to pectoral-fin ray 9 (vs. to pectoral-fin rays 12–19) and lower counts of vertebrae (57), and dorsal- (50), and anal-fin rays (44) (vs. 61–66, 56–60, and 50–54, respectively) ( Imamura & Nobetsu 2002; this study).

Figures

FIGURE 2. Pectoral girdle in five species of Careproctus with a reduced pelvic disk. Careproctus barbatulus sp. nov., FAKU 146634, paratype, 220.8 mm SL (A); Careproctus barbatulus sp. nov., FAKU 147740, non-type (B); Careproctus longibarbatus sp. nov., FAKU 148477, paratype, 223.0 mm SL (C); C. spinulosus sp. nov., FAKU 146632, paratype, 199.8 mm SL (D); C. mederi, FAKU 148478, non-type, 143.6 mm SL (E); C. gilberti, FAKU S4869, non-type, 67.2 mm SL (F). Shaded areas represent cartilage.

FIGURE 3. Distributional records of species of Careproctus with a reduced pelvic disk based on the present and previous studies (see text).

FIGURE 4. Careproctus longibarbatus sp. nov., HUMZ 124178, paratype, 216.8 mm SL, (fresh) (A); HUMZ 121570, paratype, 218.6 mm SL, (preserved) (B); ventral view of head region of HUMZ 121571, paratype, 175.6 mm SL (C), and HUMZ 121570 (D) (both preserved). Dotted red line and arrows indicate position of anus and pelvic disk, respectively.