Careproctus lacrima, new species

urn:lsid:zoobank.org:act: 22CE355B-89E3-40D8-8872- 92B6E1C87A70

Teardrop Snailfish

Figures 1C, 2C, 3C, 4; Table 1

Careproctus sp. J: Orr et al., 2019: 33, table 3 (molecular phylogenetics).

Holotype.— UW 200024 (out of UW 49434), 50.2 mm, ripe female, Aleutian Islands, north of Tanaga Island, 52.00388N, 177.82788W, 111 m depth, F/ V Sea Storm, cruise 200201, haul 118, J. W. Orr, 11 July 2002.

Paratypes.— 30 specimens, 31.4–60 mm. SIO 20-14 (ex UW 200029), 58.5 mm, 52.87148N, 171.32238W, 207 m depth, F/ V Vesteraalen, cruise 200001, haul 75, W. C. Flerx, 11 June 2000; SIO 20-15 (ex UW 200048), 53.3 mm, 51.29438N, 179.38928E, 141 m depth, F/ V Ocean Explorer, cruise 201801, haul 124, N. E. Roberson, 12 July 2018; UW 49434 *, 45–47.5 mm, 52.00388N, 177.82788E, 111 m depth, F/ V Sea Storm, cruise 200201, haul 118, in 95% ethanol, J. W. Orr, 11 July 2002, collected with holotype; UW 159754, 45.2 mm, 52.23788N, 173.40398W, 109 m depth, F/ V Sea Storm, cruise 200401, haul 57, J. W. Orr, 18 June 2004; UW 200025, 60 mm, 52.80438N, 171.54258W, 210 m depth, F/ V Dominator, cruise 200001, haul 81, benthic bag, K. P. Maslenikov, 11 June 2000; UW 200026, 52.2 mm, 52.35188N, 174.53838W, 116 m depth, F/ V Dominator, cruise 200001, haul 101, benthic bag, K. P. Maslenikov, 15 June 2000; UW 200027, 47.6 mm, 51.97308N, 176.08418E, 85 m depth, F/ V Dominator, cruise 200001, haul 227, K. P. Maslenikov, 20 July 2000; UW 200028, 40.0 mm, 51.86538N, 177.76278E, 112 m depth, F/ V Vesteraalen, cruise 199701, haul 188, 28 July 1997; UW 200030, 42 mm, 51.60578N, 178.86128W, 250 m depth, F/ V Vesteraalen, cruise 200001, haul 128, W. C. Flerx, 21 June 2000; UW 200031, 2, 44.8–46.2 mm, 51.82228N, 177.6798E, 133 m depth, F/ V Vesteraalen, cruise 200001, haul 149, W. C. Flerx, 27 June 2000; UW 200032, 50 mm, 52.05918N, 176.39518E, 162 m depth, F/ V Vesteraalen, cruise 200001, haul 176, 6 July 2000; UW 200033, 43.5 mm, 51.92538N, 178.39188E, 90 m depth, F/ V Vesteraalen, cruise 200201, haul 155, benthic bag, R. N. Clark, 6 July 2002; UW 200034, 31.4 mm, 51.88998N, 179.73528E, 93 m depth, F/ V Sea Storm, cruise 200201, haul 129, J. W. Orr, 14 July 2002; UW 200035, 46.8 mm, 52.09408N, 172.42878W, 163 m depth, F/ V Sea Storm, cruise 200201, haul 164, benthic bag, R. C. Harrison, 28 July 2002; UW 200036, 50.0 mm, 52.24858N, 173.0918W, 139 m depth, F/ V Sea Storm, cruise 201001, haul 80, N. E. Roberson, 3 July 2010; UW 200037, 47.7 mm, 51.71638N, 175.78438E, 93 m depth, F/ V Sea Storm, cruise 201001, haul 133, N. E. Roberson, 16 July 2010; UW 200038, 2, 50.0–54.0 mm, 51.64168N, 177.45318W, 133 m depth, F/ V Sea Storm, cruise 201001, haul 163, benthic bag, K. P. Maslenikov, 25 July 2010; UW 200039, 47.0 mm, 51.9318N, 176.67298E, 147 m depth, F/ V Sea Storm, cruise 201401, haul 158, G. R. Hoff, 18 July 2014; UW 200040, 51.0 mm, 52.27538N, 173.38688W, 121 m depth, F/ V Sea Storm, cruise 201801, haul 56, N. E. Roberson, 23 June 2018; UW 200041, 45.0 mm, 52.73158N, 169.85188W, 195 m depth, F/ V Sea Storm, cruise 201901, haul 1, P. Von Szalay, 24 May 2019; UW 200042, 50.6 mm, 52.84168N, 171.43278W, 204 m depth, F/ V Gladiator, cruise 200401, haul 36, benthic bag, K. P. Maslenikov, 15 June 2004; UW 200043, 49.0 mm, 51.97678N, 176.80388E, 134 m depth, F/ V Gladiator, cruise 200401, haul 141, M. Martin, 11 July 2004; UW 200044, 2, 49–51.2 mm, 51.97748N, 176.80288E, 128 m depth, F/ V Gladiator, cruise 200401, haul 142, N. Laman, 11 July 2004; UW 200045, 43.0 mm, 51.29468N, 179.38998E, 140 m depth, F/ V Gladiator, cruise 200401, haul 169, R. N. Clark, 19 July 2004; UW 200046, 50.4 mm, 51.9358N, 173.71478W, 104 m depth, F/ V Ocean Explorer, cruise 201001, haul 54, W. C. Flerx, 23 June 2010; UW 200047, 50.0 mm, 51.61778N, 178.19008W, 131 m depth, F/ V Ocean Explorer, cruise 201001, haul 148, 20 July 2010.

Diagnosis.— Careproctus lacrima is distinguished from all other described North Pacific species of Careproctus by having a small teardrop-shaped body, with loose thin skin, and anterior dorsal-fin rays buried in tissue. Among species of the C. canus species group (Orr et al., 2019), Careproctus lacrima is most similar to small C. canus, differing in having seven preoperculomandibular pores (vs. six in C. canus), lower counts of dorsal-fin rays (47–52 vs. 51–55) and vertebrae (53–57 vs. 55–60), and a smaller maximum size (60 mm vs. 198 mm). Careproctus lacrima is also similar to C. spiraki and C. maslenikovae but is further and readily distinguished from them in lacking small, rounded bumps on its body and in having a single chin pore (vs. two chin pores), higher counts of pectoral-fin rays (32–38 vs. 28–32 in C. spiraki and 26–29 in C. maslenikovae), vertebrae (53–57 vs. 42–46 and 42–43), dorsal-fin rays (47–52 vs. 38–43 and 38– 40), and anal-fin rays (43–45 vs. 32–37 and 32–33).

Description.— Body teardrop-shaped, deep and rounded anteriorly, tapering posteriorly, moderately compressed, depth at dorsal-fin origin 75.8–103.6 (88.5) % HL. Body posterior to anal-fin origin short to moderately long, about 49.4–59.2 (56.2) % SL. Head large, 27.7–33.6 (29.5) % SL, broadly rounded from nape to snout to pectoral-fin insertion. Snout rounded, slightly projecting beyond upper jaw, longer than orbit, 24.7–32.1 (29.5) % HL. Mouth small, maxilla 35.6–43.2 (38.5) % HL, extending to mid-orbit, oral cleft extending anterior to orbit, jaws terminal. Premaxillary tooth plates matching mandibular tooth plates. Premaxillary and mandibular teeth broadly trilobed in a broad band of 9–12 oblique rows of 6–9 teeth per row. Diastema absent at symphysis of upper and lower jaws. Orbit small, diameter 19.7–26.6 (25.0) % HL, dorsal margin well below dorsal contour of head, suborbital depth to oral cleft 50.0–100.0 (59.5) % OL; pupil tiny, reduced to a pinpoint. Interorbital space moderately broad, fleshy width 21.4–36.0 (35.1) % HL, bony width 12.0–23.0 (23.0) % HL, convex. Nostril single, in well-developed tube at level with upper part of orbit; nostril tube length 1.9–8.1 (8.1) % HL, 8.8–32.4 (32.4) % OL.

Pores of cephalic lateralis large: nasal pores two, maxillary pores six, preoperculomandibular pores seven, suprabranchial pores one (pore pattern 2-6-7-1); chin pore single. Interorbital pore absent. Free neuromasts not evident.

Gill opening small, 16.3–30.3 (21.0) % HL, upper margin at level of mid-orbit or dorsal part of orbit, extending to just above pectoral fin. Opercular flap rounded. Branchiostegal rays six.

Dorsal-fin rays 47–52 (51; Table 1), anterior 4–5 rays buried in tissue, uniserial and unsegmented, more posterior rays biserial and segmented; all rays simple. Anterior 15 rays not exserted; more posterior rays slightly exserted. Anteriormost dorsal-fin pterygiophore inserted between neural spines three and four or four and five (three and four), bearing a single ray.

Anal-fin rays 43–45 (44; Table 1), anterior ray unsegmented, more posterior rays biserial and segmented; all rays simple. Anterior 5–6 rays not exserted; more posterior rays slightly exserted. One or two anal-fin pterygiophores each bearing a single ray anterior to first haemal spine. Anal-fin origin below vertebrae 12–13 (caudal vertebrae 2–3).

Pectoral fin moderately notched, with 32–38 (35) rays (Table 1). Upper lobe of 25–32 (29) rays extending to anal-fin origin or beyond to anal-fin ray three, dorsalmost rays lengthening to rays 6–7, more ventral rays gradually shortening to shortest ray of notch. Lower lobe short, with 6–8 (6) rays, extending just past anus; dorsal rays gradually lengthening to thick and fleshy rays 2–3, ventral rays more slender and gradually shortening to ventralmost ray near pectoral symphysis. Tips of rays 5–50 % free of membrane, lower rays more strongly exserted. Rays in notch slightly more widely spaced than rays of lobes. Uppermost pectoral-fin ray level with lower part of orbit. Lowermost pectoral-fin ray below posterior rim of orbit.

Proximal pectoral radials four (1 þ 1 þ 1 þ 1), robust; all radials round, unnotched, radial four not widely spaced from radial three (Fig. 3C). All fenestrae absent. Scapula small, with strong helve and rounded base, lacking distinct posterior arm; coracoid broadly triangular with broad lamina. Distal radials present at base of all but first pectoral-fin ray, more ventral distal radials smaller.

Pelvic disk moderate in size, 24.7–37.9 (30.4) % HL, round, slightly longer than wide, anterior lobe moderately developed, flat with margins often turned slightly down or up. Anus much closer to pelvic disk than to anal-fin origin.

Principal caudal-fin rays 11–13 (11; Table 1), dorsal procurrent rays 2, ventral procurrent rays 1–2 (1). Membrane of posterior dorsal-fin rays attached to caudal fin 35.6–56.8 (51.4) % CL; posterior anal-fin rays, 37.0–75.0 (62.5) % CL.

Skin thin, fragile, prickles tiny, in patches, apparently easily lost; bumps absent. Pyloric caeca seven, thick, length about 35% HL.

Vertebrae 53–57 (55), 10–11 (10) precaudal, 43–47 (45) caudal (Table 1). Pleural ribs 2–3, present on vertebrae 9–10 or 8–10, anteriormost short and slender, those more posterior long and slender. Hypural plate composed of dorsal and ventral plates divided by split about 50% length of plate. Single epural present.

The largest specimen examined was a 60.0 mm ripe female (UW 200025). The smallest female with yolked eggs was 43.5 mm (UW 200033). The largest male examined was 47.5 mm (UW 49434); no males examined had enlarged, swollen testes.

Coloration.— In life, body pale, mostly translucent, small white spots over head to nape, faint darker pigment scattered internally over posterior part of body (Fig. 1C). Flash of white covering belly from pectoral fin base to near anal-fin origin. Pectoral fins unpigmented, translucent; pelvic disc white; median fins translucent, rays with faint pigment. Iris brassy. Peritoneum and orobranchial cavity pale; stomach, intestines, pyloric caeca, and urogenital papilla pale. When preserved, body uniformly pale with scattered fine dark speckling (Fig. 2C).

Distribution.— Careproctus lacrima has been collected only in the Aleutian Islands, from off Kiska Island (176.88E) to north of Amukta Island (171.38W) at depths of 90–207 m (Fig. 4).

Etymology.— The specific epithet refers to the translucent and tear-drop shaped body. It is derived from the Latin lacrima for tear or teardrop to be treated as a noun in apposition.