Allinectes curilanus Orr 2025, new combination
Creators: name: Orr, James Wilder
Publisher: name: Zenodo
Year: 2025
Subjects: Biodiversity
Taxonomy
Animalia
Chordata
Actinopterygii
Cottiformes
Liparidae
Allinectes
Allinectes curilanus

description: 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 spaced from radial three (Fig. 6A). Three large ovoid fenestrae present: scapular fenestra and fenestra between radials one and two ovoid, fenestra between one and two moderately elongate dorsoventrally, fenestra between two and three smaller, not joined to radial three. Anterodorsal margin of basal cartilage rounded, distinct hook absent. Scapula broad, with short robust helve; coracoid narrowly triangular with broad lamina. Distal radials present at base of pectoral-fin rays two to 27, more ventral distal radials reduced, absent from base of ventralmost five rays, which articulate directly with non-staining fibrocartilage.
Pelvic disk small, length 19.0–36.2 (35.3)% HL, slightly longer than wide, width 14.6–34.6 (34.6)% HL, anterior lobe well developed, flat, distance from tip of snout to pelvic disk 9.7–12.8 (12.5)% SL. Anus below dorsal-fin origin, closer to pelvic disk than anal-fin origin, distance from pelvic disk 6.8–28.0 (9.0)% HL, distance from anal-fin origin 31.1–74.5 (74.4)% HL; distance from snout to anus 18.4–23.5 (20.8)% SL, 96.6–115.3 (100.0)% HL.
Caudal fin slender, truncate. Principal caudal-fin rays 10–11 (Table 1), dorsal procurrent rays 1–2 (2), ventral procurrent rays 0–1 (1) (1–2 + 5/5-6 + 0–1) (2 + 5/5 + 1). Caudal fin 33.8–50.9 (43.7)% HL. Membrane of posterior dorsal-fin rays attached to caudal fin at slightly shorter distance than anal-fin rays: dorsal-fin rays attached to caudal fin 13.6–36.7 (25.8)% CL; anal-fin rays, 15.9–40.8 (27.6)% CL. Depth at base of caudal fin 15.9–24.1 (24.1)% CL.
Vertebrae 53–59 (54), precaudal 9–10 (10), caudal 43–49 (44; Tables 1, 2). Pleural ribs 2 or 3 (3), anteriormost small when 3, others long and slender, present on vertebrae 9–10 or 8–10 (8–10). Hypural plate composed of dorsal and ventral plates divided by a small distal notch.
Skin thin, prickles absent. Pyloric caeca 6–7 (6), short, stubby, length about 15% HL, left side of visceral cavity.
Coloration. Body and fins dusky light red in life, with faint areas of dusky mottling (Fig. 4A); belly with bright white extending from pectoral-fin base to anal-fin origin, from just lateral to midline on the ventrum, dorsally to level of ventral margin of gill slit; dark peritoneum showing in broad region dorsally between the white belly and dusky red of body. Caudal-fin margins dark red, rays in center light red or unpigmented. Iris silver. Body and fins pale in preservation. Peritoneum dusky to lightly speckled with fine dots; orobranchial cavity, stomach, intestines, pyloric caeca, and urogenital papilla pale.
Life history. The largest specimen examined, a ripe female with yolked eggs, was 80 mm (UW 201507). The smallest ripe female with yolked eggs was 61.3 mm (UW 201179; Fig. 4A). Ripe yolked eggs were about 4.0 mm in diameter. The smallest ripe male was 64.4 mm (UW 48109); the largest, 65.2 mm (UW 117504).
Distribution. The lectotype and paralectotype of Allinectes curilanus were collected in the Kuril Islands (Fig. 1). All other known material was collected throughout the Aleutian Islands from just west of Attu Island to the east among the Islands of Four Mountains (Fig. 1). Collection depths range from 240 to 471 m.
Etymology. The specific epithet curilanus refers to the Kuril Islands, the type locality.
Comparisons. Allinectes curilanus was described from the type and cotype taken in the same haul off Simushir Island in the Kuril Islands (Gilbert & Burke 1912b). Both are still in good condition, except for broken anteriormost rays, unlike the types of two of the other three previously described species of Allinectes, A. ectenes and A. attenuatus.
In both the original description and the revision of Burke (1930), A. curilanus was compared with A. ectenes alone. Following Gilbert & Burke (1912b), Burke (1930) listed the following characters as differentiating A. curilanus from A. ectenes: a shorter body, larger disk, and larger gill slit, as well as the absence of a “dorsal notch,” pyloric caeca present, higher number of pectoral rays, vent closer to the disk, and general body coloration. Among these characters, additional material of A. curilanus examined here verifies differences from A. ectenes in the relative length of the anterior part of the body (e.g., a shorter snout to pelvic disk distance, shorter pre-dorsal-fin, and typically shorter snout to anal length) and in pyloric caeca, but reveals broad overlap in numbers of pectoral-fin rays, pelvic-disk size, gill-slit size, and the position of the anus relative to the pelvic disk. The reddish body color of A. curilanus in my material versus Gilbert’s (1896) description of color in life of A. ectenes as uniform dusky brown also serves to distinguish the two species. In addition, the prominent pointed snout of A. curilanus is distinctive, unlike that of A. ectenes, in which the snout was described as “shovel-shaped with truncate snout” (Gilbert & Burke 1912b) and “bluntly rounded” in Burke (1930). The broad protruding snout is still evident in one of the types. The anterior dorsal-fin rays are broken in the lectoype, but in the paralectotype, a shallow notch is evident, despite a broken anteriormost ray.
Burke (1930) indicated that the distance from disk to anus distinguished A. curilanus from A. ectenes. However, although all the types in adequate condition are females and differ in this distance (9.0–9.6% HL in A. curilanus, vs. 15.8–22.4% HL in A. ectenes), in my additional material of A. curilanus, this distance varies widely, exhibits no sexual dimorphism, and overlaps broadly (6.7–28.0% HL for all material of A. curilanus) with the distance in A. ectenes.
Among species of Careproctus of the North Pacific, small specimens of C. simus are also similar to A. curilanus in having an elongate body and strongly protruding snout, but differ in having a black caudal fin and dark margins on the dorsal and anal fins, as well as higher counts of vertebrae (61 vs. 53–59 in A. curilanus) and median-fin rays (dorsal- 54–58 and anal-fin rays 47–51 vs. 48–54 and 42–49, respectively). Several other species of Careproctus also have strongly protruding snouts, including C. laperousei Chernova, Thiel & Eidus, 2020 described from deep waters off the Kuril Islands (Chernova et al. 2020), as well as C. leptorhinus Andriashev & Stein, 1998, C. tricapitidens Andriashev & Stein, 1998, and C. falklandicus Lönnberg, 1905 of the Southern Ocean, but all differ markedly in body shape, among other characters (Andriashev & Stein 1998).
description: Published as part of Orr, James Wilder, 2025, Resurrection of the snailfish genus Allinectes (Teleostei: Cottiformes: Liparidae) for seven North Pacific species, including descriptions of three new species from Alaska, pp. 301-334 in Zootaxa 5609 (3) on pages 314-320, DOI: 10.11646/zootaxa.5609.3.1, http://zenodo.org/record/15215135