Allinectes ectenes

Allinectes ectenes (Gilbert, 1896) Shovelhead Snailfish Figure 1, Tables 1 and 2 Careproctus ectenes Gilbert, 1896: 442 (original description). Type locality:Aleutian Islands, north of Unalaska Island, Albatross station 3331, 350 fms.— Jordan & Evermann 1896: 452 (checklist).— Jordan & Evermann 1898: 2136 (description, subgenus Allurus, in key), 2866 (type species of new subgenus Allinectes).— Gilbert & Burke 1912a: 80 (compared with C. attenuatus).— Gilbert & Burke 1912b: 372–373 (compared with C. pycnosoma and C. curilanus).— Burke 1930: 110 (description, designation of lectotype, in key).— Jordan et al. 1930: 403 (checklist, Aleutian Islands, subgenus Allinectes).— Böhlke 1953: 136 (type catalog).— Kido 1985: 16 (compared with C. pycnosoma [in part = Allocareproctus tanix Orr & Busby, 2006]).— Kido 1988: 198 (compared with A. jordani (Burke, 1930)).— Orr & Busby 2001: 57 (comparison with Prognatholiparis ptychomandibularis Orr & Busby, 2001).— Orr & Busby 2006: 4, 13 (comparison with Allocareproctus).— Maslenikov et al. 2013: 14 (in part, Alaska).— Parin et al. 2014: 319 (checklist, expected in Commander Islands).— Murasaki et al. 2018: 241 (list of characters, compared with C. surugaensis Murasaki, Takami & Fukui, 2018).— Orr et al. 2019: 25 (subgenus). Careproctus (Allurus) ectenes Jordan & Evermann 1896: 452 (new subgenus, type by monotypy, objectively invalid); Jordan & Evermann 1898: 2136 [cited by Burke 1930]. Careproctus (Allinectes) ectenes Jordan & Evermann 1898: 2866 (new subgenus, type by monotypy, replacement name for Allurus). Allinectes ectenes Burke 1930: 8 (new combination). Lectotype. USNM 48618, ca. 67 mm, (“the largest 78 mm ” [TL?] in type lot of Gilbert 1896; specimen now in poor condition in two pieces), ripe female, Aleutian Islands, 3.5 km north of Unalaska Island, 54.0278°N, 166.8139°W, Albatross station 3331, 637 m (350 fms) depth, 21 August 1890 (designated by Burke 1930). Paralectotypes. CAS-SU 3091, ca. 62 mm, and USNM 53031, ca. 60 mm; both from the same locality as lectotype and in very poor condition, both now in three pieces. Additional Material Examined. USNM 64043, 2, ca. 58–60 mm (both in very poor condition, disintegrating, in more than three pieces), Aleutian Islands, Bowers Bank, north of Rat Islands, ca. 54.3°N, 178.3°W, Albatross station 3785, 494 m (270 fms) depth, 27 June 1900. Diagnosis. Distinguished from all other species of Allinectes except A. curilanus and A. attenuatus by its higher counts of median-fin rays and vertebrae (dorsal-fin rays 48–51 vs. 42–47, anal-fin rays 44 vs. 37–41, vertebrae 54 vs. 47–51 in A. pycnosoma, A. istiophorus, new species, A. nanstanorum, new species, and A. busbyi, new species, combined), smaller pelvic disk (27.6–28.3% vs. 29.0–41.4% HL), and smaller gill slit (18.7% vs. 20.3–29.5% HL). Differing from A. curilanus in peritoneum pale (vs. dusky in A. curilanus), narrower interorbital width (13.3–15.4% vs. 16.9–21.7% HL), longer anterior body (snout to pelvic disk 66.1–68.6% vs. 49.3–65.1% HL; snout to anus 114–116% vs. 96.6–115.3% HL), and absent, filamentous, or short pyloric caeca (14.2% vs. 15.1–29.0% HL). Differing from A. attenuatus in its longer anterior dorsal-fin rays, deeper body (depth at anal-fin origin 46.7–61.5% vs. 38.8% HL in A. attenuatus), typically more dorsal-fin rays (48–51 vs. 48), fewer pectoral-fin rays (30–32 vs. 34), and peritoneum pale (vs. black). Further differing from A. istiophorus, new species, in peritoneum and stomach pale (vs. both dark in A. istiophorus, new species), fewer pyloric caeca (0–6 vs. 7–11), more vertebrae and median-fin rays (54 vs. 48–51 vertebrae, 48–51 vs. 43–47 dorsal-fin rays, and 44 vs. 38–41 anal-fin rays), broader head (width 58.4–61.4% vs. 44.3–58.6% HL), and typically smaller pelvic disk (27.6–28.3% vs. 29.7–41.4% HL). Differing from A. nanstanorum, new species, in peritoneum pale (vs. black in A. nanstanorum, new species), truncate caudal fin (vs. dorsalmost caudal-fin ray longer and thicker), more vertebrae and median-fin rays (54 vs. 47–49 vertebrae, 48–51 vs. 42–45 dorsal-fin rays, and 44 vs. 37–38 anal-fin rays), and deeper body at pelvic disk (61.6–69.2% vs. 44.2–52.8% 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), protruding snout (vs. blunt, non-protruding), shorter head (20–25% vs. 26.9% SL), and anus nearer pelvic disk (15.8–22.4% vs. 25.7% HL). Description. Body extremely elongate, slightly tapered, rounded anteriorly, compressed posteriorly; depth at pelvic disk 61.6–69.2 (69.2)% HL; depth at anal-fin origin 46.7–61.5 (53.9)% HL. Head moderately small, 20–25 (20)% SL, width 58.4–61.4 (58.4)% HL, depressed, shovel shaped, with truncate or slightly protruding snout, nape not elevated. Snout depressed, rounded, snout tip projecting anterior to lower jaw for up to distance of about half (lectotype [Burke 1930]) or equal to pupil diameter. Snout shorter than orbit, 80.9–95.1 (95.1)% OL, 25.9–29.1 (29.1)% HL, snout tip slightly or strongly projecting, 24.4–42.5 (24.4)% OL, 7.4–13.4 (7.4)% HL. Mouth inferior; upper jaw 33.9–39.6 (39.6)% HL, maxilla extending to anterior part of orbit, oral cleft extending to anterior rim of orbit; mandible 41.1–48.8 (41.1)% HL. Premaxillary and mandibular teeth trilobed in 10 oblique rows of 8 teeth forming narrow bands. Orbit 30.6–32.0 (30.6)% HL, dorsal margin below dorsal contour of head, suborbital depth to upper jaw 7.9–9.7 (9.7)% HL, to lower jaw 18.1–24.6 (24.6)% HL; pupil round, about 30–40% OL. Interorbital space broad, bony distance 13.3–15.4 (14.7% HL, convex. Nostril single, with raised rim in lectotype, or in short tube, 1.6% HL. Free neuromasts not evident because of damage. Gill opening small, 18.7% HL in lectotype, upper margin at about level of dorsal rim of orbit, extending ventrally to above pectoral fin. Dorsal-fin rays 48–51 (48; Tables 1, 2), anteriormost ray moderately elongate, 2.6–3.2 (3.2) in head, 31.3% HL, forming “distinct” notch, tip of anteriormost ray exserted (Burke 1930). Anteriormost dorsal-fin pterygiophore inserted between neural spines 2 and 3. Pre-dorsal-fin length 25% SL. Anal-fin rays 44 (Tables 1, 2), two anal-fin pterygiophores anterior to first haemal spine, each bearing single ray, tips of anterior rays exserted (Burke 1930). Anal-fin origin below vertebra 12 (caudal vertebra 2), pre-anal-fin length 34–36 (34)% SL. Pectoral fin deeply notched, with 30–32 (30) rays (Tables 1, 2). Upper lobe with 25 rays, extending well beyond anus to anal-fin origin, 71.6–81.1 (71.6)% HL, longer than lower lobe. Lower lobe elongate, 52.0–62.7 (62.7)% HL, with 7 rays, extending beyond anus short of anal-fin origin. Elongate rays of lower lobe mostly free of membrane (Gilbert 1896). Notch strong. Uppermost pectoral-fin ray level with ventral rim of orbit. Insertion of lowermost pectoral-fin ray below mid-orbit. Pelvic disk small, length 30.8% HL, slightly wider than long, width 23.1–30.8 (30.8)% HL, anterior lobe weakly developed, flat, distance from tip of snout to pelvic disk 14% SL. Anus behind vertical from gill slit (Burke 1930), closer to pelvic disk than to anal-fin origin, distance from disk to anus 15.8–22.4 (22.4)% HL, distance from anus to anal-fin origin 54.5–68.5 (54.5)% HL; distance from snout to anus 24% SL, 114.2–116.4 (116.4)% HL. ......continued on the next page Caudal fin slender, truncate, of about eight rays; dorsal- and anal-fin membranous connections to caudal apparently not greater than 30% caudal-fin length (Burke 1930). Vertebrae 54, precaudal 10, caudal 44 (Tables 1, 2). Pleural ribs 3 (USNM 53031), anteriormost small, others long and slender, present on vertebrae 8–10. Skin thin. Pyloric caeca 0–6 (absent in lectotype), if present “very short” (14.2% HL) or as “filaments” (Burke 1930). Coloration. In life, nearly uniform dusky-brownish; lighter on snout, belly, and underside of head (Gilbert 1896). Peritoneum, stomach, and intestines pale; orobranchial cavity dusky (Gilbert 1896; Burke 1930). Body and fins dusky pale in preservation. Life history. The largest specimen known is 87 mm TL (Burke 1930). The lectotype (USNM 48618) is a ripe female, 64 mm SL with yolked eggs. Distribution. Allinectes ectenes is known from only five specimens taken in the Aleutian Islands at depths of 494 and 640 m (Fig. 1). The three types were collected from north of Unalaska Island. Two additional non-type specimens of USNM 64043 identified by Burke (1930) were collected 150 miles north of the Rat Islands on Bowers Bank (Townsend, 1901) (Fig. 1). The stated locality of USNM 64043 for station 3785 from Townsend (1901) is “Rat Ids., Aleutian Chain, S. 150 m,” in which “S” is presumed to mean “South,” is likely an error. The map of stations provided by Townsend (1901) shows the station listed with 3784 (“3784-5”) as being well north of the Aleutians and listed under the general heading “North of Aleutian Islands.” Stations 3784 and 3786 are both on Bowers Bank, about 250 km north of the Rat Islands, and both were occupied on the same day. To travel 500 km from north to south of the Rat Islands and back between the two stations within the same day would be impossible. In addition, depths 250 km south of the Aleutians are in the thousands of meters, far deeper than the stated depth. Etymology. The specific epithet is derived from the Greek έχτευής, meaning “extended” or “drawn out” (Jordan & Evermann 1898) in reference to its elongate body. Remarks. Although I obtained some new data from the types of A. ectenes, all are in very poor condition. Each is broken, two are in three pieces, and all are otherwise damaged. In addition, Gilbert (1896) and Burke (1930) based their explicit descriptions on the lectotype (the largest of the syntypes), but it is unclear which specimens Burke (1930) used for his synopsis and remarks. They likely included a non-type lot of two specimens (USNM 64043), each now