Abstract
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).
Highlights
Members of the family Liparidae, comprising over 430 species in ca 30 genera, exhibit great diversity in morphology, as well as in geographic and habitat range (Chernova et al 2004; Nelson et al 2016; Orr et al 2019), and they occur worldwide in warm-temperate to cold water habitats ranging from the intertidal to depths exceeding 8,000 m (Nelson et al 2016; Gerringer et al 2017)
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) (Garman 1899; Kido 1988; Mecklenburg et al 2002; Love et al 2005; Baldwin and Orr 2010; Nakabo and Kai 2013; Murasaki et al 2018, 2019a, b)
P. flammeus differs from P. mento in having 6 caudal-fin rays and greater preanal length (29.9–35.3% SL vs 26.7–28.5% SL), and from P. mandibularis in having 17–20 pectoral-fin rays and a longer pectoral-fin lower lobe (16.7–23.4% SL vs. 13.8–15.9% SL)
Summary
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 (Chernova et al 2004; Nelson et al 2016; Orr et al 2019), and they occur worldwide in warm-temperate to cold water habitats ranging from the intertidal to depths exceeding 8,000 m (Nelson et al 2016; Gerringer et al 2017). Most closely resembling Paraliparis mento Gilbert, 1892 and Paraliparis mandibularis Kido, 1985, the specimens have an oblique mouth and a pectoral fin below a horizontal through the posterior maxillary margin but are clearly distinguishable from the latter two species in other morphological characters, as well as DNA barcoding sequence data. They are described as members of a new species. Paraliparis mandibularis, a rare species previously known only from the holotype and one non-type specimen (Kido 1988), is redescribed here in detail on the basis of the holotype and seven newly collected specimens from southern Japan
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