Careproctus barbatulus, 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 : 194-197

Careproctus barbatulus sp. nov. Kai, Matsuzaki & Mori

New Japanese name: Isaribi-bikunin

Figs. 1 , 2A, 2B ; Table 1

urn:lsid:zoobank.org:act:3DD80080-00E2-4BE3-B2A8-DB813B690CE2

Holotype. FAKU 147240, 157.7 mm SL, female, off Rausu , Hokkaido, Japan, ca. 500–800 m depth, F/ V Houyu-maru, Aug. 2019, coll. by Koji Matsuzaki, Shigeki Fujimoto, and Shigetada Fujimoto.

Paratypes. HUMZ 235308 (ex. FAKU 146599 ), 154.2 mm SL, male, 44.033ºN, 145.383ºE, off Rausu , Hokkaido, Japan, 570–825 m depth , F/ V Houyu-maru, Aug. 2018, coll. by Koji Matsuzaki , Shigeki Fujimoto, and Shigetada Fujimoto ; FAKU 146633, 190.3 mm SL, female, off Rausu, Hokkaido, Japan, ca. 500–800 m depth , F/ V Houyu-maru, 8 Sep. 2014, coll. by Koji Matsuzaki , Shigeki Fujimoto, and Shigetada Fujimoto ; FAKU 146634, 220.8 mm SL, male, off Rausu, Hokkaido, Japan, ca. 500–800 m depth , F/ V Houyu-maru, 10 Sep. 2014, coll. by Koji Matsuzaki , Shigeki Fujimoto, and Shigetada Fujimoto ; FAKU 146807–146810 , 4 (3 females, 1 sex unknown), 93.9–186.1 mm SL, off Rausu , Hokkaido, Japan, coll. by Koji Matsuzaki , Shigeki Fujimoto, and Shigetada Fujimoto (no further collection data) ; FAKU 147238 , male, 160.7 mm SL, collected with holotype ; FAKU 147910–147913 , 147915 , 148026 , 3 males and 3 females, 155.1–177.6 mm SL, 44.024ºN, 145.308ºE, off Rausu , Hokkaido, Japan, 540–750 m depth , F/ V Houyu-maru, Aug. 2020, coll. by Koji Matsuzaki , Shigeki Fujimoto, and Shigetada Fujimoto ; FAKU 148872, 199.2 mm SL, male, HUMZ 235309 (ex. FAKU 148880 ), 2 females, 169.0– 191.8 mm SL , FAKU 148980, 173.4 mm SL, male, off Rausu, Hokkaido, Japan, 500–800 m depth , F/ V Houyu-maru, Jul.–Aug. 2021, coll. by Koji Matsuzaki , Shigeki Fujimoto, and Shigetada Fujimoto ; OS 26590 (ex. FAKU 147239 ), 153.8 mm SL, female, collected with holotype ; OS 26591 (ex. FAKU 147914 ), 124.3 mm SL, female, 44.024ºN, 145.308ºE, off Rausu , Hokkaido, Japan, 540–750 m depth , F/ V Houyu-maru, Aug. 2020, coll. by Koji Matsuzaki , Shigeki Fujimoto, and Shigetada Fujimoto .

Other material. FAKU 147740 , C&S, off Rausu , Hokkaido, Japan, ca. 600–800 m depth, F / V Houyu-maru, 20 Jul. 2020, coll. by Koji Matsuzaki, Shigeki Fujimoto, and Shigetada Fujimoto .

Diagnosis. A species of Careproctus with the following combination of characters: vertebrae 55–58; dorsal-fin rays 50–53; anal-fin rays 45–48; pectoral-fin rays 27–34; pectoral fin with shallow notch, lower lobe short, extending slightly posterior to anus; pelvic disk rounded, greatly reduced; cephalic pores 2-6-7-2, chin pores paired in separate pits; gill slit moderately large, extending ventrally to pectoral-fin rays 4–10; teeth simple or slightly shouldered; anus located below mid-orbit; peritoneum and stomach black.

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

Body moderately deep, compressed, tapering posteriorly ( Fig. 1 ). Skin relatively thick, covered by cactus-like prickles; gelatinous tissue under skin moderately developed. Head large, moderately compressed, dorsal profile rounded from nape to snout. Snout rounded, not protruding anterior to mouth. Mouth moderately large, terminal, slightly oblique (or horizontal); maxilla extending to mid orbit; oral cleft extending to anterior rim of orbit. Premaxillary teeth simple or weakly shouldered, arranged in oblique rows of 10 (6–10) teeth per row forming broad band; inner teeth larger, recurved. Mandibular teeth simple or weakly shouldered, arranged in oblique rows of 9 (4–9) teeth per row forming broad band; inner teeth larger, recurved. Narrow diastema at symphysis of upper and lower jaws. Orbit of moderate size, rounded; pupil rounded. Nostril single, with short tube, level with mid-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 moderately large, upper margin level with mid-orbit, extending ventrally to pectoral-fin ray 5 (4–10). Gill rakers 7–9, short, with tiny spines on tips (not counted in holotype). Opercular flap blunt, pointed posteriorly; tip level with ventral rim of orbit. Pyloric caeca 15 (14–22), thick, moderately long, covering half of stomach, on center-left side of visceral cavity.

Vertebrae 57 (55–58), precaudal 10 (9–10) and caudal 47 (46–49). Pleural ribs minute, thin, in 1 pair (1 or 2 pairs) on abdominal vertebra 9 (8–10). Dorsal-fin rays 51 (50–53), not exserted. Anteriormost dorsal-fin pterygiophore inserted between neural spines 3 and 4 (or 4 and 5), bearing a single ray (sometimes rayless). Anal-fin rays 46 (45–48), not exserted. Two (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 7 (7–9), 3 (3–4) and 4 (4–5) rays on upper and lower hypurals, respectively, dorsal procurrent rays 1 (0–1), ventral procurrent rays 0 (0–1). Hypural plates fused with terminal vertebral centrum and parhypural, upper and lower hypural plate separated by distinct slit.

Pectoral fin moderately notched, with 30 (27–34) rays; upper lobe with 23 (20–25) rays, extending just beyond (or slightly anterior to) level of anal fin origin; lower lobe short, with 7 (7–10) rays, 4 th (5 th –7 th) ray from ventralmost longest, extending slightly posterior to anus. 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 level with mouth corner. Lowermost pectoral-fin base slightly anterior to (or below) anterior rim of orbit. Pelvic disk rounded, greatly reduced (sometimes modified as lobe). Anus much closer to pelvic disk than to anal fin origin, located below mid-orbit.

Pectoral girdle (based on FAKU 146634 and 147740: Fig. 2A, B ): Proximal pectoral radials 3 or 4; upper radials 1 or 2, hour-grass shaped with two notches, equally spaced, radials 2 or 3 (lowermost within upper radials) with one notch, radial 4 rounded squarish, widely separated from upper radials. Interradial fenestrae 2 or 3, extending between scapula and radials 1–3; fenestra 1 roundish, fenestrae 2 and 3 roundish or elliptical, sometimes with notch. Scapula broadly Y-shaped, with robust helve. Coracoid diamond-shaped or a roundish triangle, with short thin helve. Distal radials present at base of pectoral-fin rays 2 to 21–27, absent from base of ventralmost 7–8 rays.

Coloration ( Fig. 1 ): When fresh (based on FAKU 148026), head and body pale to dark reddish; tip of nostril dark brown; postorbital region and belly somewhat paler. Iris dark silvery. Dorsal, anal, and caudal fins pale to dark reddish; pectoral fin dark red, basal part paler. Pelvic disk white. When preserved, head and body white; upper and lower jaws mottled with black; nostril margined with black. Eyes black. Oral and branchial cavities pale; peritoneum and stomach black.

Reproduction. The holotype (FAKU 147240) was an immature female. FAKU 147911 (170.8 mm SL) was a spent female with yolked (2.41–2.80 mm diameter) and small immature (less than 0.50 mm diameter) eggs. FAKU 148880 (169.0 mm SL and 191.8 mm SL) were also spent females with yolked (2.97–3.48 mm diameter and 2.81– 3.38 mm diameter, respectively) and small immature (less than 0.50 mm diameter in both specimens) eggs. Yolked eggs were rounded.

Distribution. Known only from the southern Sea of Okhotsk, off Rausu, Hokkaido, Japan, at depths of 500–825 m ( Fig. 3 ).

Etymology. The specific name “ barbatulus ” derived from the diminutive form of Latin “barba” (barbel), refers to the short lower lobe of the pectoral fin, reminiscent of a short barbel.

Remarks. Within the C. gilberti species group, C. barbatulus sp. nov. shares some morphological characters with C. mederi and C. ostentum , including a short lower lobe of the pectoral fin, extending slightly posterior to the anus, and relatively thick skin with strong prickles. The new species can be distinguished from the latter two species by the gill slit length (extending to pectoral-fin ray 4–10 vs. 12–15 in C. mederi and 8–17 in C. ostentum ) ( Mecklenburg et al. 2002; this study) and coloration of the peritoneum (dark or black vs. pale with black dots). In addition, Careproctus mederi differs from the new species by having the lower end of the pectoral girdle protruding anteriorly (vs. not protruding, see description below). Although Careproctus acanthodes Gilbert & Burke, 1912 , a member of the C. rastrinus species group, has the shortest pectoral fin lower lobe among the species group, the present new species clearly differs from C. acanthodes in having a smaller pelvic disk (0.4–0.9% SL vs. 4.2– 7.6% SL) ( Orr et al. 2015). Among the species of Elassodiscus , Elassodiscus tremebundus Gilbert & Burke, 1912 also has a relatively short pectoral fin lower lobe. However, together with the diagnostic characters of the genus, E. tremebundus is further distinguishable from C. barbatulus in having a single suprabranchial pore (vs. 2 in C. barbatulus ) ( Kai et al. 2020).

Figures

FIGURE 1. Careproctus barbatulus sp. nov., FAKU 148026, paratype, 152.7 mm SL, (fresh) (A); FAKU 147240, holotype, 157.7 mm SL, (preserved) (B); ventral view of head region of FAKU 147240 (C), and FAKU 148026 (D) (both preserved). Dotted red line and arrows indicate position of anus and pelvic disk, respectively.

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).