Careproctus pulcher Chernova, Thiel & Eidus, 2020

Chernova, Natalia, Thiel, Ralf & Eidus, Irina, 2020, Four new species of Careproctus (Cottoidei: Liparidae) from the deep-water vicinity of the southern Kuril Islands (Western North Pacific), Zootaxa 4821 (1), pp. 71-87 : 79-84

Careproctus pulcher Chernova, Thiel & Eidus , new species

English name: Handsome snailfish

( Fig. 6–7 , 8 A–B, 10 A)

urn:lsid:zoobank.org:act:A651A28B-6AF6-4938-932C-57D8A05D13B8

Holotype: ZMH 26373, 115 mm TL, 100 mm SL, Pacific entrance of the Bussol Strait, 46°36.465´N, 151° 34.6´E, Agassiz trawl, depth 2350–2358 m, 24 July 2015, R / V “ Akademik M. A. Lavrentyev ”, cruise 71, station 8–7, collector I. Eidus. The specimen is an immature female (stage II).

Paratypes: ZMH 26371 (2); juvenile, 38 mm SL and male 116 mm TL, 110 mm SL. Same locality data as holotype. The testes of the male are milky, at the stage of maturity III .

Diagnosis. A species of Careproctus with the following combination of characters: vertebrae 46 (10–11+3536), D 42–43, A 35–36. Pleural ribs 3 pairs. P 31–32. Hypural one, slitted. C 10 (principal rays). Head in adults 25.5–26.3 % SL, preanal length 39 % SL. Eye 28.2–28.5 % lc. Pelvic disk 31.4–32.3 % lc. Pores 2-6-7-1. Gill slit reaching to 4 th pectoral-fin ray. Fresh color bright reddish-orange; peritoneum pale.

Description. Fresh specimens. Body elongated and low. Skin naked. Gelatinous tissue covering the basal part of dorsal and anal fins. Color of head, pectoral fin, and entirely body is intensive reddish-orange; rays of dorsal, anal and caudal fins orange. Male has a wide dark band on head across eye area. Body of juveniles translucent.

Preserved specimens (data of holotype, those of paratype 110 mm SL in parentheses). Body low, greatest depth 6.1 (6.3) in SL, gradually declining from occiput to tail. Head 3.9 (3.8) in SL. Head height 61 (57) % lc, about equal to head width, 63 (60) % lc. Head dorsal contour gradually decreases anteriorly. Nostril short tubular and rather wide, at level of upper edge of eye. Snout protrudes noticeably above the upper jaw. Snout fold deep and overhanging the upper lip; pores nasal 1 and infraorbital 1–3 open on its very edge. Tissue of chin rather dense, forming an angular edge, on lower surface of which preoperculomandibular pores 1–3 sitting. Eye large (28 % lc). Interorbital distance equal to eye. Mouth terminal, horizontal; angle of oral cleft under front edge of eye. Palatine oral valve covered with papillae. Teeth trilobed, in regular oblique rows, 5–6 (6–8) teeth in anterior rows on both jaws. Gill slit equal to eye diameter, reaching to the 4 th pectoral-fin ray. Opercular flap large and angled, protruding well above the pectoral-fin base; the end of the flap level with upper margin of eye. Cephalic pore pattern 2-6-7-1. Pores on the front of snout slightly enlarged, the others small. Chin pores are not close together.

Radiograph (two paratypes in parentheses, if differs). Vertebrae 46: precaudal 11 (10–11), caudal 35 (35–36). Dorsal-fin rays 42 (43), precaudal rays 9 (8–9). Anal-fin rays 36 (35), two (one or two) anterior rays before first haemal spine. Rayless pterygiophores absent; anteriormost dorsal-fin ray inserted between neural spines 3 and 4. Pleural ribs 3 pairs on 9–11 th vertebrae, all strong. Hypural one, slitted. C 2+5/5+1; principal rays 10.

Dorsal-fin origin above the base of pectoral fin. Dorsal and anal fins uniformly low and overlap the caudal fin at about a half and one third of caudal-fin length accordingly.

Pectoral fin notched; upper lobe about 16% SL, almost reaching to anal-fin origin. Lower lobe shorter (75–76 % of upper lobe length), not reaching to anus. Dorsalmost pectoral-fin ray level with the lower margin of eye. Symphysis of pectoral fins located below posterior margin of eye. Рectoral-fin rays 31 (23+8) in the holotype, 31–32 (24–25+7) in paratypes.

Pelvic disk flattened and rather large, 31.4 (32.3) % lc, slightly exceeding the eye; segmental pads present; the marginal part dense but thin, with the pelvic rays visible. Disk lies under the area from the middle of postorbital distance to gill slit. Anus opens closer to disk than to anal-fin origin, at a distance of two third of disk length behind the disk.

Skin thin and naked, slightly gelatinous and translucent, so that branches of the facial nerve are clearly visible through the skin on the interorbital region and snout.

Ural papilla in females and urogenital papilla in males present; they are small, conical and do not exceed in length 1/4 disk diameter.

Preserved specimens are discolored, pink pigmentation is entirely absent. Peritoneum, oral and gill cavities pale. In female, head is completely light; in male, a distinct gray band (melanophore pigmentation) present across the eye. The same differences in head color can be seen in two juveniles ( Fig. 8 A–B).

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The 38 mm SL juvenile is generally similar to adult specimens, including having a thin disk structure. There are size-related differences in the proportions ( Table 2). In particular, the anus is located closer to the middle of the distance from the disk to anal-fin origin. The end of the opercular lobe is above eye level.

Distribution. Careproctus pulcher was found at the Pacific entrance of the Bussol Strait, at a depth of 23502358 m.

Environmental conditions. Bottom sediments in the box-corer at the place of capture included coarse-grained black sand, gravel and stones. The ground from the Agassiz trawl was a mixture of sand, pebbles and stones. Large fragments of dead and living glass sponges were numerous. The largest groups of invertebrates were isopods (at least 5 species) and caprellids attached to colonies of hydroids (5–6 species); benthopelagic shrimps (2 or 3 species), gastropods and ophiurids were found in small quantities.

Etymology. The name is derived from the Latin word pulcher , meaning handsome, because of the elegant proportions and beautiful fresh color of the fish.

Comparative notes. Careproctus pulcher has 46 vertebrae, 43–43 dorsal-fin rays. Among the congeners of the northern part of the Pacific Ocean, with relatively few vertebrae (44–58) are the species C. abbreviatus Burke , C. opisthotremus Gilbert & Burke , C. simus Gilbert , C. attenuatus Gilbert & Burke , C. faunus Orr & Maslenikov , С. rotundifrons and C. notosaikaiensis Kai, Ikeguchi & Nakabo ( Gilbert 1896; Gilbert & Burke 1912 b; Burke 1930; Orr & Maslenikov 2007; Sakurai & Shinohara 2008; Kai et al. 2011; Ji et al., 2012). However, meristic counts in C. abbreviatus are lower (vertebrae ca. 44, D 39) and in the remaining species are higher (vertebrae 52–61, D 45–56) than in C. pulcher . Careproctus pulcher differs from all of them also by the presence of one suprabranchial pore (vs. the pore pattern 2-6-7-2). Moreover, C. abbreviatus , C. attenuates , С. rotundifrons and C. notosaikaiensis have a black or brown peritoneum. The eye in C. simus is larger (33.0 % lc). In C. faunus the eye is larger as well (31.746.0 % lc, in average 33.0 %) and gill opening longer (16.7–27.0 % lc, in average 25.8 %). All these species inhabit the shelf and the upper part of the slope, whereas C. pulcher is found at a depth of over two thousand meters.

By number of vertebrae and rays of C. pulcher is closest to the species C. lycopersicus (the Bering Sea and the eastern Aleutian Islands, depths 304–1096 m) and C. kamikawai Orr (Monterey Bay and the southern California coast, 468–1397 m), which have D 40–46, A 34–38, C principal 10–12 ( Orr 2012). Careproctus pulcher differs from C. lycopersicus by shorter gill opening (reaching ventrally to 4 th pectoral ray vs. 8–12 th ray in the latter; length 7.0–7.5 vs. 10.7–14.5 % SL); pectoral-fin number is fewer (31 vs. 33–38), head shorter (25.5–26.3 % SL vs. 28.1–32.1 % SL). Careproctus pulcher differs from C. kamikawai in having a pale peritoneum (vs. black), terminal mouth (vs. subterminal), and the absence of the notch in dorsal fin (the anterior fin portion is separated by shallow notch in the latter).

From similar depths not many congeners are known. Among these species, C. pulcher differs from C. surugaensis (Suruga Trough, 1450– 570 m) by fewer vertebrae (46 vs. 50) and D (42–43 vs. 47) and a pale peritoneum (black in the latter) ( Murasaki et al. 2017).

Figures

FIGURE 6. Careproctus pulcher sp. nov., fresh specimens, female, holotype, ZMH 26373 (above) and male, paratype, ZMH 26371 (below).

FIGURE 7. Careproctus pulcher sp. nov., museum specimens, A–B, female 100 mm SL, holotype, ZMH 26373; paratypes, ZMH 26371: C, male 110 mm SL; D, juvenile 38 mm SL.

FIGURE 8. Fresh juveniles: A–B, Careproctus pulcher sp. nov., 38 and ca. 48 mm SL; C, holotype of Careproctus globulus sp. nov., 43 mm SL, ZMH 26374.