Allinectes nanstanorum, Orr, 2025

Allinectes nanstanorum , new species

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Burnt Red Snailfish

Figures 1 View FIGURE 1 , 2C View FIGURE 2 , 4C View FIGURE4 ; Tables 2 View TABLE 2 and 3 View TABLE 3

Holotype. UW 200685 , 79.4 mm, ripe female, Bering Sea, Pribilof Canyon , 56.0155°N, 168.8866°W, 1172 m depth, 17 July 2016, F/V Cape Flattery, cruise 2016-01, haul 111, N. E. Roberson. GoogleMaps

Paratype. UW 158017 , 77.7 mm, ripe female, Bering Sea, 56.2255°N, 171.4857°W, 866 m depth, 11 July 2012, F/V Vesteraalen , cruise 2012-01, haul 130, S. Kotwicki GoogleMaps .

Diagnosis. Distinguished from all other species of Allinecte s by its unique caudal fin having a longer and thicker dorsalmost fin ray, dark body coloration, more slender body, narrower interorbital width (13.3–14.2% vs. 14.3–25.0% HL in other species of Allinectes ) and, except from A. curilanus and A. istiophorus , by its less depressed head (depth at pelvic disk 44.2–52.8% vs. 61.4–76.3% HL). Further differing from A. ectenes , A. curilanus , and A. attenuatus in its lower counts of total vertebrae (47–49 vs. 53 or more) and median-fin rays (42–45 vs. 48 or more dorsal-fin rays, and 37–38 vs. 40 or more anal-fin rays). Most similar to Allinectes istiophorus and A. busbyi , differing in anterior dorsal-fin rays shorter (vs. strongly elongate in A. istiophorus and moderately elongate in A. busbyi ), anterior body length shorter (snout to anus length 87.8–91.5% vs. 96.9–111.7% and 105.4% HL), body overall dark red and black (vs. light red), stomach pale (vs. dark), and abdomen dark (vs. white or pale). Further differing from A. ectenes in peritoneum black (vs. pale in A. ectenes ), body less deep at pelvic disk (44.2–52.8% vs. 61.6–69.2% HL), and pelvic disk larger (29.0–29.8% vs. 30.8% HL). Further differing from A. curilanus in snout tip slightly protruding beyond lower jaw (vs. strongly protruding lower jaw in A. curilanus ). Also similar to A. attenuatus , known only from holotype, but differing in having body deeper at anal-fin origin (44.2–51.7% vs. 38.8% HL), pre-anal-fin length longer (34.9–35.4% vs. 32.5% SL), and anus closer to disk (13.6–14.9% vs. 24.7% HL) and farther from anal-fin origin (58.0–67.6% 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 ), head shorter (22.2–24.2% vs. 26.9% SL), and anus far from the pelvic disk (13.6–14.9 vs. 25.7% HL).

Description. Body elongate, slightly tapered, slightly depressed anteriorly, becoming rounded and compressed posteriorly; depth at pelvic disk 44.2–52.8 (52.8)% HL; depth at anal-fin origin 44.2–51.7 (51.7)% HL. Head moderately small, 22.2–24.2 (22.2)% SL, width 41.0–48.9 (48.9)% HL, broadly depressed, nape slightly elevated. Snout rounded, slightly shorter or longer than orbit, 89.3–123.5 (89.3)% OL, 28.4–33.5 (28.4)% HL. Snout tip projecting slightly anterior to lower jaw, 14.3–21.5 (14.3)% OL. Mouth inferior; upper jaw 33.0–41.5 (33.0)% HL, maxilla extending to mid-orbit, oral cleft extending to anterior rim of orbit; mandible 41.5–46.3 (41.5)% HL. Premaxillary and mandibular teeth trilobed in 8–9 (9) oblique rows of 7–9 (9) teeth forming narrow bands. Orbit 27.1–31.8 (31.8)% HL, dorsal margin below dorsal contour of head, suborbital depth to upper jaw 8.0–12.5 (12.5)% HL, to lower jaw 20.2–26.1 (26.1)% HL. Interorbital space broad, fleshy distance 28.4–30.3 (28.4)% HL, bony distance 13.3–14.2 (14.2)% HL, convex. Nostril with raised rim or slightly longer, at level with midorbit; nostril tube length 3.6–15.7 (3.6)% OL.

Free neuromasts 4–5, extending posteriorly from suprabranchial pore 2. Gill opening 23.4–26.1 (26.1)% HL, upper margin at level of midorbit or dorsal rim of orbit, extending ventrally to just above pectoral-fin. Gill rakers 6 ( Table 2 View TABLE 2 ).

Dorsal-fin rays 42–45 (45; Tables 2 View TABLE 2 , 3 View TABLE 3 ), three anteriormost rays slightly elongate, 27.3–34.0 (27.3–33.0)% HL, longer than more posterior rays, deeply emarginate, membrane damaged in both specimens, followed by shorter rays 3 and 4, forming moderate notch. Anteriormost dorsal-fin pterygiophore inserted between neural spines 3 and 4. Pre-dorsal-fin length 23.7–24.4 (24.4)% SL.

Anal-fin rays 37–38 (38; Tables 2 View TABLE 2 , 3 View TABLE 3 ); one or two (one) anal-fin pterygiophores anterior to first haemal spine, each bearing single ray, tips of all rays not exserted. Anal-fin origin below vertebrae 13–14 (caudal vertebrae 2–3), pre-anal-fin length 34.9–35.4 (34.9)% SL.

Pectoral fin deeply notched, with 30–31 (31) rays ( Tables 2 View TABLE 2 , 3 View TABLE 3 ). Upper lobe 71.6–76.1 (71.6)% HL, with 21–22 (22) rays extending well beyond anus to anal-fin origin, longer than lower lobe. Lower lobe elongate, 59.7–78.7 (59.7)% HL, with nine rays, extending well beyond anus halfway to anal-fin origin; dorsal rays lengthening to elongate rays. Tips of rays 5–20% free of membrane, elongate rays of lower lobe up to 60% free of membrane. Notch strong. Uppermost pectoral-fin ray level with ventral rim of orbit. Insertion of lowermost pectoral-fin ray below posterior part of orbit.

Pelvic disk moderately small, length 29.0–29.8 (29.0)% HL, slightly longer than wide, width 26.7–29.3 (26.7)% HL, anterior lobe weakly developed, distance from tip of snout to pelvic disk 12.1–12.5 (12.1)% SL. Anus below dorsal-fin origin, much closer to pelvic disk than anal-fin origin, distance from disk 13.6–14.9 (13.6)% HL, distance from anal-fin origin 58.0–67.6 (67.6)% HL; distance from snout to anus 20.3–21.2 (20.3)% SL, 87.8–91.5 (91.5)% HL.

Caudal fin asymmetrical, with dorsalmost ray longer and thicker than more ventral rays. Principal caudal-fin rays 11 ( Table 2 View TABLE 2 ), dorsal procurrent rays 2, ventral procurrent rays absent (2 + 5/6 + 0). Caudal fin 60.6–73.3 (73.3)% HL. Dorsal-fin rays attached to caudal fin 28.1–31.0 (31.0)% CL; anal-fin rays, 29.8–32.6 (32.6)% CL. Depth at base of caudal fin 13.2–15.8 (13.2)% CL.

Vertebrae 47–49 (49), precaudal 10, caudal 37–39 (39; Tables 2 View TABLE 2 , 3 View TABLE 3 ). Pleural ribs 3, anteriormost small, others long and slender, present on vertebrae 8–10. Hypural plate composed of dorsal and ventral plates divided by a large split of about 75% length of plate.

Skin thin, loose. Pyloric caeca 5, long, length about 21% HL, left side of visceral cavity.

Coloration. Body overall red with darker mottling in life ( Fig. 4C View FIGURE4 ); head dark externally, lighter red at margins, dark orobranchial cavity also showing through operculum; belly nearly completely dark, faint white anteriorly at pectoral-fin base; peritoneum dark. Iris dark.All fin rays red. In preservation, body dusky overall, head dark between tip of snout and nape, snout tip light, belly dark except for light vent, fins pale. Peritoneum black; orobranchial cavity dark; stomach, intestines, pyloric caeca, and urogenital papilla pale.

Distribution. The two known specimens of Allinectes nanstanorum were collected on the Bering Sea continental slope ( Fig. 1 View FIGURE 1 ) south of Zhemchug Canyon at 866 m depth and in Pribilof Canyon at a depth of 1172 m.

Life history. Both specimens examined were ripe females with yolked eggs. Yolked eggs were 2.1–3.2 mm in diameter.

Etymology. The specific epithet is an abbreviated amalgamation of the first names of the collectors of the holotype (Nancy Roberson) and the paratype (Stan Kotwicki) in the genitive case, both of the Alaska Fisheries Science Center, U.S. National Marine Fisheries Service.

Remarks. Both specimens of A. nanstanorum are in similar condition, adequate but not ideal, which is typical for snailfishes taken in deeper benthic trawls. Fin rays are stripped, although not broken, and the bodies are somewhat contorted.

Among species of Careproctus , A. nanstanorum is similar in general body morphology and external color to C. pulcher but differs in having a black peritoneum (vs. pale in C. pulcher ), elongate anterior dorsal-fin rays (vs. rays uniform in size), and higher counts of vertebrae (47–49 vs. 46) and anal-fin rays (anal-fin rays 37–38 vs. 35–36). It is also similar to C. opisthotremus Gilbert & Burke 1912a , known from only two specimens, differing from it in having a dark peritoneum (vs. pale in C. opisthotremus ), much smaller gill slit ending above the pectoral fin (vs. extending to pectoral-fin ray 5), and more slender head and body (depth at pelvic disk 10.7–11.8% SL vs. 16.5% SL).