Research Article |
Corresponding author: Yoshiaki Kai ( kai.yoshiaki.4c@kyoto-u.ac.jp ) Academic editor: Nina Bogutskaya
© 2020 Yoshiaki Kai, Kenta Murasaki, Ryo Misawa, Atsushi Fukui, Eisuke Morikawa, Yoji Narimatsu.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Kai Y, Murasaki K, Misawa R, Fukui A, Morikawa E, Narimatsu Y (2020) A new species of snailfish of the genus Paraliparis (Liparidae) from the western North Pacific, with a redescription of the poorly known species Paraliparis mandibularis. ZooKeys 968: 143-159. https://doi.org/10.3897/zookeys.968.56057
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A new snailfish, Paraliparis flammeus, is described on the basis of 18 specimens collected off the Pacific coast of Tohoku District, northern Japan at depths of 422–890 m. The new species is distinguished from 28 species of Paraliparis described from the North Pacific by the following combination of characters: mouth oblique; uppermost pectoral-fin base below horizontal through posterior margin of maxillary; 60–63 vertebrae, 54–58 dorsal-fin rays, 50 or 51 anal-fin rays, six principal caudal-fin rays, and 17–20 pectoral-fin rays. A maximum likelihood tree based on 106 COI gene sequences (492 bp) of Paraliparis recovered a monophyletic group comprising P. flammeus, Paraliparis cephalus, and Paraliparis dipterus. Paraliparis cephalus is similar to P. flammeus in having an oblique mouth, but it has four caudal-fin rays (vs six rays) and the uppermost pectoral-fin base above a horizontal through the maxillary posterior margin. Paraliparis dipterus differs from P. flammeus in having a horizontal mouth, 12–14 pectoral-fin rays, and lacking pyloric caeca (present in P. flammeus). Paraliparis flammeus is most similar to the eastern North Pacific Paraliparis mento in having an oblique mouth and the uppermost pectoral-fin base below a horizontal through the posterior margin of the maxillary. However, P. flammeus differs from P. mento in having six caudal-fin rays (vs five rays) and greater preanal length (29.9–35.3% SL vs 26.7–28.5% SL). A poorly known species, Paraliparis mandibularis, previously known from only two specimens collected from Tosa Bay, southern Japan, is redescribed based on the holotype and seven newly collected specimens. It is also similar to the new species but has 27–30 pectoral-fin rays and a shorter pectoral-fin lower lobe (13.8–15.9% SL in P. mandibularis vs 16.7–23.4% SL in P. flammeus).
Japan, Paraliparis cephalus, Paraliparis flammeus sp. nov., Paraliparis mento, taxonomy, Tohoku
Members of the family Liparidae (snailfishes), comprising over 430 species in ca 30 genera, exhibit great diversity in morphology, as well as in geographic and habitat range (
Along the Pacific coast of Tohoku District, northern Honshu Island, Japan, continuous surveys for resource assessments of ground fishes by the Tohoku National Fisheries Research Institute, Japan Fisheries Research and Education Agency, have resulted in the discovery of several new species (
Methods for counts and measurements follow
For DNA barcoding, we attempted to include all the available sequences of congeneric or related species (see
All specimens were collected by R/V Wakataka-maru, otter trawl.
Paraliparis flammeus is distinguished from other species of Paraliparis by the following combination of characters: mouth oblique; uppermost pectoral-fin base below a horizontal through posterior margin of maxillary; 60–63 vertebrae, 54–58 dorsal-fin rays, 50 or 51 anal-fin rays, 6 principal caudal-fin rays, and 17–20 pectoral-fin rays; pectoral radials 4, moderately large and located medially.
Measurements are shown in Table
Body
compressed, elongate, deepest at nape, strongly taping posteriorly (Fig.
Skeleton of Paraliparis flammeus sp. nov. A, B C&S specimens,
Dorsal-fin rays 56 (54–58); anteriormost ray above tip of opercle, posteriormost ray attached membranously to dorsalmost caudal-fin ray. Anteriormost dorsal-fin pterygiophore inserted between neural spines 3 and 4 (2 and 3, or 3 and 4), bearing a single ray. Anal-fin rays 51 (48–51); posteriormost ray attached membranously to ventralmost caudal-fin ray. Vertebrae 63 (60–63), comprising precaudal 9 and caudal 54 (51–54). Pleural ribs absent. Hypurals and parhypural fused into single plate. Caudal fin slender, posterior margin slightly rounded (or truncate). Principal caudal-fin rays 6, dorsal principal rays 3, ventral principal rays 3, no procurrent rays. Pyloric caeca 7 (4–6), short and finger-like, on left side of visceral cavity. Anus below posterior margin of preopercle (or midway between posterior margin of preopercle and posterior rim of orbit).
Pectoral fin moderately notched, with 19 (17–20) rays; upper lobe with 14 (12–15) rays, extending beyond (or just reaching) anal-fin origin; lower lobe elongate, with 5 (3–7) rays, uppermost ray of lower lobe longest, extending beyond anus, not reaching (reaching) anal-fin origin. Uppermost pectoral-fin base below a horizontal through posterior margin of maxillary. Lowermost pectoral-fin base below anterior rim of orbit (or below midway between tip of snout and anterior rim of orbit). Rays between upper and lower lobes widely spaced.
Selected osteological characters. Roof of cranium comprising frontal and supraoccipital incompletely closed; frontal and supraoccipital poorly ossified; parietal absent (Fig.
Coloration. In fresh specimens, head and body pale pink with fine melanophores; margin of preopercle silvery; anteroventral portion silvery, with dark peritoneum visible through thin skin; dorsal and anal fins crimson, distal margins somewhat darker; pectoral fin crimson (Fig.
Reproductive characters. Ovary pouch-like, whitish; one of two ovaries with 33 ripe ovarian eggs (2.06–2.12 mm in diameter) and numerous unripe ovarian eggs (0.6 mm in maximum diameter) in female paratype (
The specific epithet flammeus is from Latin, meaning “flame”, and refers to the crimson fin coloration of the species.
Alignment of the COI gene sequences (492 bp) determined herein with previously determined sequences of Paraliparis resulted in a maximum likelihood tree based on 101 aligned sequences and the recovery of a monophyletic group comprising P. flammeus, P. cephalus, and P. dipterus (Fig.
Maximum likelihood phylogenetic tree of Paraliparis and related genera based on COI sequences (492 bp). Support values (≥ 50% ML bootstrap probability) indicated along branches. Each node labeled with a registration number (red, determined in this study) or an accession number deposited in INSDC or BOLD. Nectoliparis pelagicus included as out-group.
Among the 28 species of Paraliparis known from the North Pacific, P. flammeus shares the morphological characters, i.e., an oblique mouth and the uppermost pectoral-fin base below a horizontal through the posterior margin of the maxillary, with only P. mento (Washington southward to Monterey Bay), P. mandibularis (Tosa Bay, Japan), and Paraliparis angustifrons (Garman, 1899) (off Panama) (
Paraliparis mandibularis
Paraliparis mandibularis is distinguished from other species of Paraliparis by the following combination of characters: mouth oblique; uppermost pectoral-fin base below a horizontal through posterior margin of maxillary; 63–66 vertebrae, 58–61 dorsal-fin rays, 52–54 anal-fin rays, 6 principal caudal-fin rays, and 27–30 pectoral-fin rays. Proximal pectoral radials 4, enlarged and moved to anterior edge of basal lamina. Parietals present. Among North Pacific species, it is similar to P. flammeus sp. nov., which differs from the former in having 17–20 pectoral-fin rays, and to P. mento, which has 5 principal caudal-fin rays.
Measurements are shown in Table
Measurements of Paraliparis flammeus sp. nov. and P. mandibularis (means in parentheses).
Paraliparis flammeus | Paraliparis mandibularis | |||
Holotype | Paratypes | Holotype | Non-types | |
|
n = 14 |
|
n = 6 | |
Standard length (mm) | 75.8 | 42.5–80.4 | 103.6 | 104.7–128.1 |
In % of standard length | ||||
Head length | 21.4 | 17.2–24.1 (20.8) | 19.8 | 18.0–20.7 (19.8) |
Snout length | 6.7 | 5.2–7.0 (6.2) | 6.9 | 5.6–6.9 (6.1) |
Orbit length | 5.8 | 4.5–6.2 (5.4) | 5.6 | 4.4–6.0 (5.2) |
Interorbital width | 7.2 | 3.6–8.8 (5.8) | 8.0 | 5.9–7.7 (6.5) |
Maxilla length | 10.8 | 10.6–12.0 (11.1) | 10.5 | 9.7–11.1 (10.6) |
Gill slit length | 10.3 | 6.4–10.9 (8.4) | 6.9 | 7.5–10.5 (9.1) |
Body depth | 23.0 | 13.5–21.7 (18.6) | 16.1 | 16.0–24.9 (19.8) |
Pectoral-fin length | 26.2 | 18.5–26.7 (22.4) | Damaged | 21.6–26.0 (23.3) |
Pectoral-fin lower lobe length | 19.6 | 16.7–23.4 (20.6) | Damaged | 13.8–15.9 (15.1) |
Pectoral-fin notch-ray length | 13.3 | 9.1–15.9 (12.6) | Damaged | 9.6–11.8 (10.7) |
Predorsal length | 22.4 | 20.3–24.5 (22.5) | 18.5 | 19.7–23.7 (21.2) |
Preanal length | 35.3 | 29.9–35.2 (29.9) | 33.2 | 31.8–36.1 (33.8) |
Snout to anus length | 16.9 | 13.0–16.7 (14.5) | 13.2 | 12.0–18.8 (14.6) |
Caudal-fin length | 11.8 | 10.8–15.1 (12.9) | Damaged | 15.5–19.6 (17.8) |
In % of head length | ||||
Snout length | 31.3 | 24.5–35.5 (29.9) | 34.6 | 27.4–34.2 (30.9) |
Orbit length | 27.1 | 21.7–32.3 (26.1) | 28.2 | 23.2–29.0 (26.5) |
Interorbital width | 33.8 | 20.6–36.6 (27.8) | 40.5 | 29.8–35.1 (33.0) |
Maxilla length | 50.5 | 43.8–63.7 (53.7) | 52.8 | 51.8–56.3 (53.5) |
Gill slit length | 48.1 | 30.5–18.3 (40.5) | 34.7 | 37.4–51.9 (46.6) |
In % of caudal-fin length | ||||
Dorsal-fin connection to caudal fin | 37.9 | 22.3–37.7 (29.6) | Damaged | 38.4–50.6 (42.9) |
Anal-fin connection to caudal fin | 40.1 | 29.2–44.7 (36.9) | Damaged | 19.6–36.4 (29.8) |
Dorsal-fin rays 58–63; anteriormost ray above tip of opercle, posteriormost ray attached membranously to dorsalmost caudal-fin ray. Anteriormost dorsal-fin pterygiophore inserted between neural spines 3 and 4 or 4 and 5, bearing a single ray. Anal-fin rays 52–54; posteriormost ray attached membranously to ventralmost caudal-fin ray. Vertebrae 63–66, comprising precaudal 9 and caudal 54–57. Pleural ribs absent. Hypurals and parhypural fused into single plate. Caudal fin slender, posterior margin slightly rounded. Principal caudal-fin rays 6, dorsal principal rays 3, ventral principal rays 3, no procurrent rays. Pyloric caeca 5 or 6, short and finger-like, on left side of visceral cavity. Anus below posterior margin of orbit.
Pectoral fin moderately notched, with 27–30 rays; upper lobe with 17–19 rays, extending beyond (or just reaching) anal-fin origin; lower lobe elongate, with 8–13 rays, uppermost ray of lower lobe longest, extending beyond anus, not reaching anal-fin origin. Uppermost pectoral-fin base below a horizontal through posterior margin of maxillary. Lowermost pectoral-fin base below anterior rim of orbit or below midway between tip of snout and anterior rim of orbit. Rays between upper and lower lobes widely spaced.
Selected osteological characters. Roof of cranium without distinct crest comprising well ossified frontals, supraoccipital, and parietals. Opercle well ossified, sharpened posteriorly, supporting upper margin of opercular flap. Subopercle thin, comprising two spines forming a V-shape; lower spine supporting lower margin of opercular flap. Subopercle and interopercle attached. Cleithrum broad and robust, dorsal portion elongated. Proximal pectoral radials 4, enlarged occupying almost entire width of cartilaginous basal laminae and moved to anterior edge of basal lamina (Fig.
Coloration. In fresh specimens, head and body pale pink, posterior half of body reddish; dark peritoneum visible through thin skin; dorsal and anal fins pale pink, distally reddish; caudal and pectoral fins red (Fig.
Western Pacific Ocean; Tosa Bay and Bungo channel, off Shikoku Island, Japan, in depths of 600–1,092 m (
Paraliparis mandibularis was originally described by
Paraliparis flammeus is characterized by a poorly ossified cranium, a characteristic recognized elsewhere in some snailfishes, including Nectoliparis pelagicus, Pseudoliparis swirei Gerringer & Linley, 2017 and Rodichthys regina Collett, 1879 (
Paraliparis atramentatus:
We are grateful to the captain, officers, and crews of the R/V Wakataka-maru (Fisheries Research and Education Agency, Japan) for their assistance in the field. We also thank H. Endo, T. Naito, K. Mizumachi (