Allinectes curilanus Orr 2025, new combination

Allinectes curilanus (Gilbert & Burke 1912), new combination Kuril Snailfish Figures 1, 4A, 5A, 6A; Tables 1 and 2 Careproctus curilanus Gilbert & Burke, 1912b: 373, fig. 15, pl. 47-1 (original description, compared with C. ectenes, in key). Type locality: Japan, off Simushir Island, Kuril Islands, Japan, 229 fms depth, Albatross station 4803.— Burke 1930: 109, fig. 25 (description, key).— Böhlke 1953: 135 (type catalog).— Kido 1985: 12 (compared with C. simus Gilbert, 1896 and C. pycnosoma [= Allocareproctus tanix]).— Kido 1988: 198 (compared with A. jordani).— Sheiko & Fedorov 2000: 31 (questionably a synonym of C. pycnosoma).— Orr & Busby 2001: 57 (compared with Prognatholiparis ptychomandibularis).— Mecklenburg et al. 2002: 608 (questionably a synonym of C. pycnosoma).— Parin et al. 2002: S111 (synonym of C. pycnosoma).— Chernova et al. 2004: 7 (checklist, possible senior synonym of A. jordani).— Orr & Busby 2006: 13 (compared with Allocareproctus).— Parin et al. 2014: 317 (checklist, Russia, possible synonym of A. jordani, C. pycnosoma).— Murasaki et al. 2018: 240, table 2 (list of characters, compared with C. surugaensis).— Volvenko et al. 2018: suppl. p. 6 (list of trawl-caught species). Holotype. USNM 73341, 64.0 mm, female, Russia, off Simushir Island, Kuril Islands, 46.7°N, 151.75°E (46°42′ N, 151°45′ E), 419 m (229 fms) depth, 24 June 1906, Albatross station 4803. Paratype. CAS-SU 22382, 62.6 mm, ripe female, same locality as holotype. Material examined. 31 specimens, 46.6–68.7 mm: UW 200697, 55 mm, 52.0817°N, 178.1333°E, 446 m depth, 5 July 2002, F/ V Vesteraalen, cruise 2002-01, haul 151, benthic bag, R. N. Clark; UW 200998, 68.7 mm, 51.6059°N, 176.2941°W, 352 m depth, 3 July 2002, F/ V Sea Storm, cruise 2002-01, haul 86, benthic bag, J. W. Orr; UW 201434, 61.7 mm, 52.5016°N, 179.9697°E, 275 m depth, 14 July 2002, F/ V Vesteraalen, cruise 2002- 01, haul 184, benthic bag, R. N. Clark; UW 201429, 61.5 mm, 52.8350°N, 172.2932°E, 357 m depth, 1 August 2004, F/ V Gladiator, cruise 2004-01, haul 230, R. N. Clark; UW 201430, 57.2 mm, 52.8301°N, 172.2054°E, 377 m depth, 1 August 2004, F/ V Gladiator, cruise 200401, haul 229, R. N. Clark; UW 200694, 62.6 mm, 51.5952°N, 176.3367°W, 363 m depth, 30 June 2004, F/ V Gladiator, cruise 2004-01, haul 94, M. Martin; UW 201433, 63.5 mm, 51.8723°N, 178.5537°E, 405 m depth, 6 July 2002, F/ V Vesteraalen, cruise 2002-01, haul 153, benthic bag, R. N. Clark; UW 201507, 3, 60.0–80.0 mm, 52.5171°N, 179.9407°W, 396 m depth, 13 July 2002, F/ V Vesteraalen, cruise 2002-01, haul 179, benthic bag, R. N. Clark; UW 200699, 65 mm, 52.1634°N, 179.4879°E, 249 m depth, 13 July 2002, F/ V Vesteraalen, cruise 2002-01, haul 176, benthic bag, R. N. Clark; UW 117504, 65.2 mm, 51.5636°N, 178.3331°E, 471 m depth, 30 June 2000, F/ V Dominator, cruise 2000-01, haul 159, benthic bag, K. Pearson; UW 153150, 64 mm, 52.6453°N, 172.2730°W, 398 m depth, 26 June 2010, F/ V Sea Storm, cruise 2010-01, haul 68, J. W. Orr; UW 154877, 79.3 mm, 51.61001°N, 178.8626°W, 320 m depth, 6 July 2014, F/ V Sea Storm, cruise 2014- 01, haul 111, G. R. Hoff; SIO 24 -37 (ex UW 200691), 2, 64.9–71.6 mm, 53.1899°N, 169.8622°W, 404 m depth, 19 July 2002, F/ V Vesteraalen, cruise 2002-01, haul 195, benthic bag, R. N. Clark; SIO 24 -38 (ex UW 200692), 62.6 mm, 51.9421°N, 178.0728°E, 433 m depth, 28 June 2000, F/ V Dominator, cruise 2000-01, haul 150, benthic bag, K. Pearson; UW 200698, 75.6 mm, 52.8459°N, 172.3591°E, 240 m depth, 19 June 2002, F/ V Sea Storm, cruise 2002-01, haul 39, benthic bag, K. Pearson; SIO 24 -39 (ex UW 200990), 59.5 mm, 52.2844°N, 173.2471°W, 357 m depth, 30 July 2002, F/ V Sea Storm, cruise 2002-01, haul 176, benthic bag, R. C. Harrison; SIO 24 -40 (ex UW 200991), 65.4 mm, 51.6194°N, 176.2474°W, 328 m depth, 17 July 2002, F/ V Vesteraalen, cruise 2002-01, haul 191; UW 200992, 2, 46.6–54.3 mm, 51.5595°N, 177.6164°W, 375 m depth, 4 July 2002, F/ V Sea Storm, cruise 2002-01, haul 92, J. W. Orr; UW 200994, 2, 62.2–62.7 mm, 51.8716°N, 178.5523°E, 407 m depth, 6 July 2002, F/ V Vesteraalen, cruise 2002-01, haul 154, R. N. Clark; UW 201179, 2, 57.9–61.3 mm, 51.5508°N, 177.6611°W, 328 m depth, 3 July 2018, F/ V Ocean Explorer, cruise 2018-01, haul 99, N. E. Roberson; UW 48107, 52.1 mm, 53.1043°N, 169.8535°W, 290 m depth, 26 May 2000, F/ V Dominator, cruise 2000-01, haul 34, benthic bag, J. W. Orr; UW 48108, 64 mm, 51.4593°N, 178.4612°W, 285 m depth, 20 June 2000, F/ V Vesteraalen, cruise 2000-01, haul 120, benthic bag; UW 48109, 2, 64.4–74.8 mm, 51.8504°N, 178.4324°E, 395 m depth, 30 June 2000, F/ V Dominator, cruise 2000-01, haul 156, benthic bag, K. Pearson; UW 201436, 65.0 mm, 52.0859°N, 175.12°E, 385 m depth, 25 July 2004, F/ V Gladiator, cruise 2004-01, haul 191, R. N. Clark. Diagnosis. Distinguished from all other species of Allinectes except A. ectenes by a combination of moderately elongate anterior dorsal-fin rays, depressed head, and strongly protruding snout over an inferior mouth. Distinguished from the similar A. ectenes, known from a handful of specimens in poor condition, by its thicker and longer pyloric caeca (absent or filamentous when present in A. ectenes), typically more pronounced, pointed snout (vs. broadly rounded), dusky peritoneum (vs. pale, unpigmented in A. ectenes), and several morphometric characters including a narrower head (44.9–57.9% vs. 58.2–61.4% HL), wider bony interorbit (16.9–21.7% vs. 15.7–16.4% HL), and shorter snout to pelvic disk distance (49.3–65.1% vs. 66.1–68.7% HL). Further distinguished from A. istiophorus, new species, and A. pycnosoma by higher counts of vertebrae and median-fin rays: vertebrae 53–59 in A. curilanus (vs. 48–51 in A. istiophorus, new species, and A. pycnosoma combined), dorsal-fin rays 48–54 (vs. 43–47), anal-fin rays 42–49 (vs. 38–41). Differing from A. nanstanorum, new species, in lighter body color (vs. dark head and dark mottling on body in A. nanstanorum, new species), caudal fin truncate (vs. dorsalmost caudal-fin ray longer and thicker), as well as more vertebrae (53–59 vs. 47–49) and median-fin rays (dorsal, 48–54 vs. 42–45; anal, 42–49 vs. 37–38, respectively). Easily distinguished from A. attenuatus by its acute, strongly protruding snout (vs. rounded, non-protruding snout in A. attenuatus), higher counts of dorsal- and anal-fin rays (dorsal, 48–54 and anal, 42–49 vs. 48 and 40), more slender body anteriorly (depth at pelvic disk 38.7–66.7 vs. 67.1% HL), deeper body posteriorly (depth at anal-fin origin 39.7–53.0 vs. 38.8% HL), and a longer distance from anus to anal-fin origin (31.1–74.4 vs. 29.4% HL). Further distinguished from A. pycnosoma by its strongly notched pectoral fin with long lower lobe (vs. shallow notch, with short lower lobe in A. pycnosoma), and shorter head (18.6–22.7% vs. 26.9% SL). Description. Body elongate, slender, slightly tapered, rounded anteriorly, compressed posteriorly; depth at pelvic disk 38.7–66.7 (65.4)% HL; depth at anal-fin origin 39.7–53.0 (47.4)% HL. Head small, 18.6–22.7 (20.8)% SL, width 44.9–57.9 (57.9)% HL, slightly depressed, nape slightly elevated. Snout strongly projecting anterior to lower jaw. Snout including fleshy snout tip much longer than orbit, bony length typically shorter than orbit, 62.5–102.9 (62.5)% OL, 22.4–34.0 (22.6)% HL; snout tip long, 18.8–45.2 (18.8)% OL, 5.8–16.5 (6.8)% HL. Mouth inferior; upper jaw 30.1–48.2 (33.8)% HL, maxilla extending to mid-orbit, oral cleft extending to anterior rim of orbit; mandible 41.3–51.8 (45.9)% HL. Premaxillary and mandibular teeth strongly trilobed in 10 oblique rows of 7–10 teeth forming bands. Orbit 28.0–38.3 (36.1)% HL, dorsal margin below dorsal contour of head, suborbital depth to upper jaw 7.6–13.0 (12.0)% HL, to lower jaw 19.3–25.3 (22.6)% HL; pupil round. Interorbital space broad, fleshy distance 19.0–37.9 (24.8)% HL, bony distance 16.9–21.7% HL, flat. Nostril single, with well-developed tube at level with upper part of orbit; nostril tube length 2.5–13.7% OL. Free neuromasts 4–5. Gill opening small, 14.8–30.7 (20.3)% HL, upper margin at or just below level of dorsal rim of orbit, extending ventrally to above pectoral fin or to pectoral-fin ray 3. Gill rakers 4–9 (Tables 1, 2), short, blunt. Symplectic with small dorsal flange extending onto metapterygoid (Fig. 5A). Dorsal-fin rays 48–54 (49; Tables 1, 2), anterior rays moderately elongate, ray 1 28.6–62.0% HL, longer than succeeding rays, followed by rays 2–4 which are shorter, forming a shallow notch, followed by a longer ray 5 and succeeding rays, rays 1 and 2 deeply emarginate, 50–70% free from membrane, rays 3 and 4 10–20% free from membrane. Anteriormost dorsal-fin pterygiophore inserted between neural spines 2 and 3. Pre-dorsal-fin length 18.7–25.3 (25.3)% SL. Anal-fin rays 42–49 (44; Tables 1, 2), one or two (one) anal-fin pterygiophores anterior to first haemal spine, each bearing a single ray, tips of all rays not exserted. Anal-fin origin below vertebrae 11–12 (caudal vertebrae 1–2) (vertebra 12), pre-anal-fin length 27.2–37.5 (35.2)% SL. Pectoral fin deeply notched, with 28–37 (34) rays (Tables 1, 2). Upper lobe 60.5–82.9 (70.7)% HL, with 21–30 (25) rays extending well beyond anus to or slightly beyond anal-fin origin (to origin), longer than lower lobe in small (ca. <64 mm SL) individuals, about equal in larger (ca.> 64–68 mm SL) individuals, and shorter in the largest (> 68 mm SL) specimens, dorsalmost rays lengthening to rays 8–10, more ventral rays gradually shortening to shortest ray of notch. Lower lobe elongate, 47.3–94.9 (79.0)% HL, with 6–9 (9) rays, extending to or just beyond anus. Elongate rays of lower lobe mostly free of membrane, longest ray 60% free. Notch strong. Uppermost pectoral-fin ray level with ventral rim of orbit. Insertion of lowermost pectoral-fin ray below posterior part of orbit. Proximal pectoral radials four (3+1), robust; radials 1 and 2 hourglass shaped, radial three ovoid, with slight notch, radial four ovoid, unnotched, widely spa