Snailfishes of the Careproctus rastrinus complex ( Liparidae ) : redescriptions of seven species in the North Pacific Ocean region , with the description of a new species from the Beaufort Sea

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Introduction
Among the over 400 species in the family Liparidae, Careproctus Krøyer is one of the most speciose genera. Found in both the northern and southern hemispheres and in all the world's oceans, the genus contains at least 140 species (Chernova et al. 2004) and new species are regularly being recognized and described (e.g., Chernova et al. 2004;Orr 2012. Nominal species have uncommonly been synonymized, and when synonymized (e.g., Kido 1988) are often resurrected when additional data become available. The genus is diverse and as additional species are described and relationships better understood, it becomes clearer that the genus should be divided and lineages recognized as distinct taxa. However, phylogenetic analyses are thus far limited by inadequate taxonomic sampling (Kido 1988;Balushkin 1996;Knudsen et al. 2007;Smith & Busby 2014) and elevating lineages to the generic level without a clear understanding of the phylogenetic relationships among the species will likely render Careproctus paraphyletic.
More than 50 species are known from the North Pacific (Chernova et al. 2004;Imamura & Noetsu 2002;Orr & Maslenikov 2007;Kai et al. 2011a;Machi et al. 2012;Orr 2012), and among these, one group of similar species that may represent a distinct lineage is the C. rastrinus complex (Pitruk 1991;Chernova 1999) Kai et al. (2011a,b) and Nakabo & Kai (2013), as well as C. phasma Gilbert, C. spectrum Bean, and a new species herein described . These species share a characteristic anteriorly deep body that strongly tapers posteriorly ("tadpole morph" of Chernova [2005b]), a moderately sized pelvic disc about the size of the orbit, a small gill slit entirely above the pectoral fin or extending to the base of a few of its dorsal-most rays, a strongly notched pectoral fin with a moderately to strongly elongate lower lobe ("long-feather" of Chernova [2005b]), simple conical teeth, and, with the exception of some C. trachysoma, a predominately pale body with pale peritoneum. Although several of the species have been synonymized in the past because of their similarity, we consider all to be valid.
The first species of the C. rastrinus complex to be described were taken in Alaska: C. spectrum (Bean 1890) and C. phasma (Gilbert 1896). Both have been problematic, primarily because two unrelated species were included among the syntypes of C. spectrum, leading to faulty comparisons with C. phasma and other misidentifications. The poor condition of most of the types further complicated identifications.
In their review of the liparids of Japan, Gilbert & Burke (1912b) described as new most of the remaining species in the C. rastrinus species complex, including C. rastrinus, C. acanthodes, C. pellucidus, and C. trachysoma.  continued to recognize all described species in the complex as valid in his worldwide review of the Liparidae. Concurrently, treating primarily the species of Russian waters, Soldatov & Lindberg (1930) listed C. rastrinus, C. acanthodes, C. trachysoma, C. pellucidus, and C. spectrum as valid, and included descriptions of C. acanthodes, C. trachysoma, and C. spectrum based solely on the original descriptions.
Shortly after Burke's review, Chapman & DeLacy (1934) described C. scottae from southeast Alaska. They compared the new species to the western Pacific C. rastrinus in particular, acknowledging its obvious similarities, as well as noting differences from other members of the complex.
Other authors (Taranetz 1937;Schmidt 1950;Wilimovsky 1954Wilimovsky , 1958Quast & Hall 1972;Fedorov 1973;Lindberg & Krasyukova 1987) variously listed as valid all the species known in the regions they considered. Among these authors, Schmidt (1950) offered additional descriptions of new specimens from the Sea of Okhotsk, indicating significant intraspecific variation from the types in some characters within C. rastrinus and C. acanthodes. While he also provided a description of C. phasma, this was likely a misidentification based on evidence from his morphological characters and the depth of collection.
In the most recent revision of the liparids of Japan, Kido (1988) recognized as valid in the western Pacific only C. rastrinus and C. trachysoma within this group, synonymizing C. acanthodes and C. pellucidus under C. rastrinus. In both cases, he noted either slight differences in morphometric characters in the case of C. acanthodes (shorter lower pectoral lobe, smaller gill opening, shorter pelvic disk) or complete overlap in morphometric and meristic characters in C. pellucidus. He did not address the eastern North Pacific species C. scottae, C. phasma, and C. spectrum.
Nearly all later authors followed Kido (1988). Sheiko & Fedorov (2000) treated the Japanese species C. acanthodes and C. pellucidus, as well as the eastern Pacific C. scottae, as synonyms of C. rastrinus; and Mecklenburg et al. (2002), in their inventory of species of this group in Alaskan waters, listed C. acanthodes and C. pellucidus as synonyms of C. rastrinus. Their review included C. rastrinus, C. scottae, C. phasma, and C. spectrum, noting that C. scottae was likely also a synonym of C. rastrinus.

Material and methods
Counts, measurements, and descriptive terminology follow Andriashev & Stein (1998), with the exception of the cephalic sensory pore series, which follows Stein et al. (2001), and pectoral girdle morphology, which follows Orr & Maslenikov (2007). Counts of median-fin rays and vertebrae were taken from radiographs. Counts of teeth were made according to methods of Able & McAllister (1980). Counts of gill rakers were taken from the first gill arch on the right side. The right gill membrane and abdomen were cut to examine the branchial and visceral cavities; right pectoral girdles were dissected and cleared and counter stained following Potthoff (1984). Lengths are presented as standard length (SL) and proportions as percent SL, unless otherwise indicated as percent head length (HL), orbit length (OL), or caudal length (CL). Fleshy interorbital width is taken at the greatest width including tissue extending to the orbital rim; bony interorbital width is the narrowest bony width. Suborbital depth to lower jaw is measured from the ventral rim of the orbit to the mandibular articulation. Prickle density is the number of prickles counted in a line the length of the orbit diameter in a region having the highest density of prickles. Measurements and counts are presented in species accounts as the range for all material examined followed by the value for the holotype or lectotype in parentheses when intraspecific variation is indicated. Institutional abbreviations are as listed at http://www.asih.org/codons.pdf. Sequences used by Kai et al. (2011a) to recognize clades within the C. rastrinus species complex are summarized by new identifications with Genbank numbers in Table 1, including additional specimens of C. phasma sequenced for this revision. Two principal components analyses (PCA) were conducted to visualize differences among the species: one conducted on the new species and its most similar congeners (C. phasma and C. spectrum) and a second on the western Pacific species (C. rastrinus, C. trachysoma, C. acanthodes, and C. pellucidus). The analyses were conducted on the covariance matrix of log-transformed morphometric characters and on the correlation matrix of meristic characters, following Kai et al. (2011a). Differences between species were illustrated by plotting scores of morphometric principal component (PC) 2 against PC3, meristic PC1 against PC2, and meristic PC1 against morphometric PC3, the axes that most clearly distinguished the species. Diagnosis. Careproctus rastrinus is distinguished from all other species of Careproctus by the combination of cytb and 16S rRNA sequences ("OKH1" of Kai et al. 2011a,b; Table 1), an anteriorly robust body covered by cactus-like prickles, the presence of a postorbital pore, a moderate-sized pelvic disc, a lower pectoral-fin lobe longer than upper lobe, a pale peritoneum, and a speckled gray stomach. It is most similar to light colored C. trachysoma of the western Pacific, from which it can be distinguished by the color of its peritoneum and stomach (pale peritoneum and speckled gray stomach vs. speckled pale and dark in C. trachysoma), and its deeper and longer head and anterior body. It is also similar to the eastern Pacific C. scottae, from which it can be distinguished by its higher counts of caudal vertebrae (51-56 in C. rastrinus vs. 48-52 in C. scottae) and anal-fin rays (51-56 vs. 47-53), speckled gray stomach (pale in C. scottae), smaller pelvic disc (9.9-26.8 vs. 13.9-26.5 % HL), and shorter nasal tube (0.9-4.7 vs. 3.2-6.4 % HL), and to C. phasma from which it can be distinguished by the postorbital pore (present in C. rastrinus vs. absent in C. phasma), smaller pelvic disc (9.9-26.8 vs. 20.1-35.9 % HL), longer upper jaw (36.6-55.1 vs. 31.4-48.1 % HL), shorter nasal tube (0.9-4.7 vs. 2.9-5.7% HL), speckled gray stomach (pale in C. phasma), higher counts of dorsal-fin rays (57-63 vs. 50-56), higher counts of anal-fin rays (51-56 vs. 43-49), and higher counts of vertebrae (62-66 vs. 55-60). It is further distinguished from C. spectrum by its higher counts of dorsal-fin rays (57-63 vs. 52-54), smaller pelvic disc (9.9-26.8 vs. 22.5-23.1 % HL), and smaller orbit (16.7-33.3 vs. 33.9-34.4 % HL).
Coloration. Body and fins orangish pink and white in life (Fig. 1A); head, dorsum from nape to caudal fin, and ventrum at anal-fin origin to caudal fin orangish pink; isthmus, base of pectoral fin, and body posterior of gill slit to anal-fin origin lighter; area above belly silvery white (crystalline guanine) with orangish-pink highlights becoming obsolete at about a quarter to half the anal-fin length; base and lower lobe of pectoral fin white; dorsal margin and distal portion of fin orangish pink; dorsal half of eye dark, silvery gray ventrally. Body and fins pale in preservation; base of fins beneath skin with pigment, showing faint line between fins and body. Peritoneum pale, speckled gray; orobranchial cavity pale; stomach gray, intestines pale to darkly mottled, pyloric caeca pale to darkly mottled, and urogenital papilla pale.    Life history. Largest specimen examined was a 385.6 mm (FAKU 131691). The only ripe female with yolked eggs was 210 mm; males 146.5-285 mm were ripe with large testes. At least two sizes of eggs were present in the ripe female: yolked eggs were about 3.1 mm in diameter and white eggs had diameters of 0.5-1.5 mm.
Distribution. Careproctus rastrinus has been collected from the Sea of Okhotsk, from west of Kamchatka south to eastern Sakhalin Island and northeastern Hokkaido Island (Fig. 6). Collection depths range from 114 to 217 m.
Etymology. The specific epithet is derived from the Latin rastrum, meaning "rake", likely a reference to the dense covering of cactus-like prickles on the types.
Remarks. Prior to our examination of type material and the availability of tissues suitable for genetic analysis, C. rastrinus had been recognized as one of the most common liparids in the Bering Sea and Aleutian Islands. Herein, we recognize C. rastrinus to be limited in geographic range to the Sea of Okhotsk, replaced in the eastern Bering Sea and Aleutian Islands by the similar species C. scottae. Records of C. rastrinus from the Pacific Ocean east of the Kuril Islands into the western Bering Sea (e.g., Orlov 2005) require verification.
We reidentified one paratype of C. rastrinus as C. acanthodes. It was among the smallest collected but was readily identified as C. acanthodes by counts of vertebrae, the large size of the pelvic disc, and short lower pectoral-fin lobe.
Coloration. Body dusky purple-orange to orangish pink (Fig. 1B,C). In darker color morphotype (Fig. 1C), fins dusky, margins dark, lighter anteriorly becoming darker posteriorly; head, dorsum from nape to caudal fin, and ventrum at anal-fin origin to caudal fin dusky purple-orange; isthmus, base of pectoral fin, and body posterior of gill slit to anal-fin origin lighter; area above belly pale to silvery white (guanine) becoming obsolete at about a quarter to half the anal-fin length; base and lower lobe of pectoral fin light with dusky areas; dorsal margin and distal portion of fin dusky; dorsal margin of eye dark, most of eye silvery white. In lighter color morphotype (Fig.  1B), body and fins orangish pink and white in life; head, dorsum from nape to caudal fin, and ventrum at anal-fin origin to caudal fin orangish pink; isthmus, base of pectoral fin, and body posterior of gill slit to anal-fin origin lighter; area above belly silvery white (guanine) with orangish-pink highlights becoming obsolete at about a quarter to half the anal-fin length; base and lower lobe of pectoral fin white; dorsal margin and distal portion of fin orangish pink; dorsal margin of eye dark, most of eye silvery white. Body and fins dusky to pale in preservation; base of fins beneath skin with pigment, showing faint line between fins and body. Peritoneum pale with scattered speckles; orobranchial cavity pale with scattered speckles; stomach dark, speckled dusky to black; intestines dark, dusky speckled to black; pyloric caeca pale to mottled, and urogenital papilla pale.
Life history. Reaching a maximum size of 350 mm (Okiyama 2004), the largest specimen examined was 264.8 mm (FAKU 131402), a ripe female with yolked eggs. The smallest ripe female with yolked eggs was 194.4 mm. Eggs were 3.6-5.0 mm in diameter. The only ripe male was 229.2 mm.
Distribution. Careproctus trachysoma has been collected from the Sea of Japan, from Hokkaido to off Oki Island, at 150-1345 m ( Fig. 6; Okiyama 2004).
Etymology. The specific epithet is derived from the Greek trakhys (τραχύς), meaning "rough", and soma (σῶμα), meaning "body", likely a reference to the covering of cactus-like prickles on the types.
Remarks. We recognize two color morphotypes within C. trachysoma (see Kai et al. 2011a,b). Lighter individuals had either been previously misidentified as C. rastrinus or recognized as a new species, and darker individuals, especially those with dark fins, identified as C. trachysoma (Kido 1988). However, no differences in morphological characters or in mitochondrial or nuclear DNA sequence data have been found between light and dark morphs (Kai et al. 2011a,b Diagnosis. Careproctus scottae is distinguished from all other species of Careproctus by the combination of cytb and 16S rRNA sequence data ("BER1" and "BER2" of Kai et al. 2011a; Table 1), an anteriorly robust body covered by cactus-like prickles, the presence of the postorbital pore, a moderate-sized pelvic disc, a lower pectoral-fin lobe longer than upper lobe, a pale peritoneum and stomach, and counts of vertebrae and median fin rays. It is most similar to C. rastrinus, from which it can be distinguished by its lower counts of caudal vertebrae (48-52 in C. scottae vs. 51-56 in C. rastrinus) and anal-fin rays (47-53 vs. 51-56), pale peritoneum and stomach (gray in C. rastrinus), a larger pelvic disc in individuals larger than 100 mm (13.9-28.8 vs. 9.9-18.8 % HL), and a longer nasal tube (3.2-6.4 vs. 0.9-4.7 % HL), and to C. phasma, from which it can be distinguished by the postorbital pore (present in C. scottae vs. absent in C. phasma), smaller pelvic disc (13.9-28.8 vs. 20.1-35.9 % HL), higher counts of dorsal-fin rays (54-61 vs. 50-56), higher counts of anal-fin rays (47-53 vs. 43-49), and higher counts of vertebrae (59-64 vs. 55-60). It is further distinguished from C. spectrum by its higher counts of dorsal-fin rays (54-61 vs. 52-54 in C. spectrum) and smaller orbit ( Pores of cephalic lateralis system of moderate size, pore pattern 2-6-7-2, chin pores paired. Interorbital pore absent. Gill opening small, 18.3-44.2 (30.1) % HL, upper margin at or just above level of dorsal rim of orbit, extending ventrally to above pectoral-fin or to pectoral-fin rays 1-8 (ray 3). Opercular flap rounded to slightly angular (rounded). Gill rakers 8-12 (Tables 2-3), short, blunt.
Coloration. Body and fins orangish pink and white in life (Fig. 3A); head, dorsum from nape to caudal fin, and ventrum at anal-fin origin to caudal fin orangish pink; isthmus, base of pectoral fin, and body posterior of gill slit to anal-fin origin white; area above belly silvery white (crystalline guanine) with orangish-pink highlights becoming obsolete posteriorly at about a quarter to half the anal-fin length; base and lower lobe of pectoral fin white; dorsal margin and distal portion of fin orangish pink; eye dark dorsally, silvery greenish gray ventrally. Body and fins pale in preservation; base of fins beneath skin with pigment, showing faint line between fins and body. Peritoneum pale to lightly speckled; orobranchial cavity pale; stomach pale to gray, intestines pale to mottled, pyloric caeca pale to mottled, and urogenital papilla pale.
Life history. The largest specimen examined was 253.8 mm (UW 117348), a ripe female with yolked eggs, and the largest specimen observed was about 390 mm from off Amchitka Island in the Aleutian Islands (AFSC 2000 survey photograph, JWO, unpublished data). The smallest ripe female with yolked eggs was 186.8 mm. Ripe yolked eggs were about 2.6 mm in diameter. The smallest ripe male was 123.9 mm; the largest, 237 mm.
Distribution. Careproctus scottae has been collected throughout the deeper waters of the eastern Bering Sea and the Aleutian Islands (Fig. 6). Collection depths range from 71 to 390 m. Previously recognized as C. rastrinus outside of Southeast Alaska, it is one of the most commonly identified species of Careproctus on the Bering Sea slope (e.g., Hoff 2013) and in the Aleutian Islands (e.g., Von Szalay et al. 2011). Records of C. rastrinus from the western Bering Sea (e.g., Orlov 2005) may be either C. scottae or C. rastrinus and require verification.
Skin relatively thick, thin gelatinous layer beneath skin, cactus-like prickles covering body, in most dense region about 10 prickles in orbit length. Pyloric caeca 19, length about 73 % HL, left side of visceral cavity.
Coloration. Body and fins dusky orangish pink and white to dusky in life; head, dorsum from nape to caudal fin, and ventrum at anal-fin origin to caudal fin dusky orangish pink; isthmus, base of pectoral fin, and body posterior of gill slit to anal-fin origin lighter; area above belly silvery white (crystalline guanine) becoming obsolete at anal-fin origin; base and lower lobe of pectoral fin white, dorsal margin and distal portion of fin dusky; base of dorsal and anal fins pigmented along body margin; eye dark dorsally, silvery ventrally. Body and fins pale in preservation; base of fins beneath skin with pigment, showing faint line between fins and body. Peritoneum pale; orobranchial cavity pale; stomach pale to white, intestines pale, pyloric caeca pale, and urogenital papilla pale.
Life history. The largest specimen examined was 104.7 mm (FAKU 130974), a ripe female. The smallest ripe female with yolked eggs was 81 mm. Egg diameters of yolked eggs were 2.3-3.7 mm. Distribution. Careproctus acanthodes has been collected from the eastern Sea of Japan, in the Gulf of Tatary off the southwest coast of Sakhalin Island, and in the Sea of Okhotsk off Cape Patience (Fig. 6), and off the west coast of Kamchatka (Lindberg and Krasyukova 1987). Collection depths range from 114 m to 582 m at the type locality.
Etymology. The specific epithet is derived from the Greek word akanthodes (ἀκανθὼδης), meaning "spiny form", a reference to the cactus-like prickles covering the bodies of the cotypes.
Remarks. Schmidt (1950) described three specimens of C. acanthodes taken in the northern Sea of Okhotsk off the western coast of Kamchatka. While noting their capture far north of the type locality in the Tatar Strait, he listed meristic data that differed from the description of type material. Although his counts of 30-31 (24-25/6) pectoral-fin rays are well within the range of our material, his counts of 55-57 dorsal-and 50-54 anal-fin rays are higher than nearly all of our material examined (six of our specimens had 55 dorsal-fin rays, all others had fewer), suggesting that he may have misidentified another species.  Table 1), an anteriorly robust body covered by scattered cactus-like prickles, the presence of the postorbital pore, a moderate-sized pelvic disc, elongate lower pectoral-fin rays, and a light peritoneum. It is most similar to C. acanthodes of the western Pacific, from which it can be distinguished by its higher number of gill rakers (9-13 in C. pellucidus vs. 7-9 in C. acanthodes), smaller pelvic disc (10.0-17.0 vs. 18.2-28.8 % HL), longer lower pectoral-fin lobe (57.2-128.8 vs. 35.7-61.2 % HL), and larger gill slit (24.4-44.9 % HL, extending to pectoral-fin rays 5-10 vs. 18.2-36.1 % HL, extending to pectoral-fin ray 2). It is also similar to C. rastrinus and C. trachysoma, from both of which it can be distinguished by its typically lower counts of median fin rays (dorsal-fin rays 51-60, anal-fin rays 46-53 in C. pellucidus vs. 57-63 and 51-57 in C. rastrinus and C. trachysoma) and total vertebrae (57-63 vs. 62-67). It is further distinguished from C. spectrum by its smaller pelvic disc (10.0-17.0 vs. 22.5-23.1 % HL).
Coloration. Body and fins pink and white in life (Fig. 2B); head, dorsum from nape to caudal fin, and ventrum at anal-fin origin to caudal fin dusky pink; isthmus, base of pectoral fin, and body posterior of gill slit to anal-fin origin lighter; area above belly silvery white (crystalline guanine) with orangish-pink highlights becoming obsolete at about anal-fin origin; base and lower lobe of pectoral fin white; dorsal margin and distal portion of fin pink; base of dorsal and anal fins pigmented along body margin; eye dark dorsally, silvery white ventrally. Body and fins pale in preservation; base of dorsal fin beneath skin with pigment, showing distinct line between fin and body. Peritoneum pale to lightly speckled; orobranchial cavity pale; stomach dark, intestines speckled, pyloric caeca pale, and urogenital papilla pale.
Life history. The largest specimen examined was a 213.9 mm male (HUMZ 67593). The smallest ripe female with yolked eggs was 132.9 mm; the largest, 175 mm. Egg diameters were 2.5-3.3 mm. One female was spent, with small white eggs 0.1-0.8 mm in diameter. The smallest ripe male examined was 136.1 mm; the largest, 140 mm. Distribution. Careproctus pellucidus has been collected from the Pacific coast of Japan, off Hokkaido and northern Honshu (Fig. 6) at depths of 145 to 300 m.
Etymology. The specific epithet is derived from the Latin pellucidus, meaning "shining through", referring to the species' thin transparent skin.
Additional material examined. A total of 119 specimens, not including the types above, 54.3-272.0 mm SL. See "Non-type material examined below." Diagnosis. Careproctus phasma is distinguished from all other species of Careproctus by the combination of cytb and 16S rRNA sequences ("ARC1", in part, and "BER3" of Kai et al. 2011a; Table 1), an anteriorly robust body that is either naked or covered with scattered cactus-like prickles, the absence of the postorbital pore, a moderate-sized pelvic disc, a lower pectoral-fin lobe longer than upper lobe, a light peritoneum and stomach, and lower counts of vertebrae and median fin rays. It is most similar to the new species C. lerikimae of the Beaufort Sea, from which it can be distinguished by its entirely pale coloration (vs. dusky body in C. lerikimae), fewer vertebrae (55-60 in C. phasma vs. 59-63 in C. lerikimae) and median fin rays (50-56 and 43-49 in C. phasma vs. dorsal 56-59 and anal 48-51 in C. lerikimae), as well as its shorter maxilla, longer lower pectoral-fin lobe, and longer nasal tube. It is also similar to C. rastrinus and C. scottae from which it can be distinguished by the presence of the postorbital pore (absent in C. phasma), larger pelvic disc (20.1-35.9 vs. 9.9-26.8 % HL), and lower counts of caudal vertebrae (44-50 vs. 48-56), dorsal-fin rays (50-56 vs. 54-63), and anal-fin rays (43-49 vs. 47-56). It is distinguished from C. spectrum by its smaller orbit (17.3-31.6 vs. 33.9-34.4 % HL).
Skin relatively thin, loose gelatinous layer particularly evident in juveniles, prickles reduced, in most dense region about 9 prickles in orbit length, or absent. Pyloric caeca 17-24, length about 28-37 % HL, left side of visceral cavity.
Coloration. Body pink and white and fins orangish pink in life (Fig. 3B); head, dorsum from nape to caudal fin, and ventrum at anal-fin origin to caudal fin pink to marginally orange; isthmus, base of pectoral fin, and body posterior of gill slit to anal-fin origin white; area above belly silvery white (crystalline guanine) with orangish-pink highlights becoming obsolete posteriorly at about anal-fin origin; base and lower lobe of pectoral fin white; dorsal margin and distal portion of fin orangish pink; eye with dark dorsal margin, becoming brassy and whiter ventrally. Body and fins pale in preservation; base of fins beneath skin with pigment, showing faint line between fins and body. Peritoneum pale; orobranchial cavity pale; stomach, intestines, and pyloric caeca pale to dusky greenish; urogenital papilla pale.
Life history. The largest specimen examined was 272.0 mm (HUMZ 73075) of unknown sex. The smallest ripe female with yolked eggs was 102.9 mm; the largest, 176.7 mm. Three egg classes were found in ripe females: yolked eggs 3.5 mm, maturing white 1.8 mm, and immature < 1 mm. The smallest ripe male was 76.3 mm; the largest, 191 mm.
Distribution. Careproctus phasma has been collected from the continental shelf of the eastern Bering Sea and the northern Gulf of Alaska (Fig. 6). Collection depths range from 57 to 184 m. Etymology. The specific epithet is taken from the Greek phasma (ϕάσμα), meaning "specter", "ghost", or "apparition." Remarks. Gilbert (1896) described C. phasma from Bristol Bay in the Bering Sea and compared it to C. spectrum, known only from the type series. Based on his description of "the much larger sucking disk and the narrow gill-slit, the latter confined to area above base of pectorals", Gilbert was clearly comparing C. phasma to C. gilberti Burke, which has a disk much smaller than the orbit and a large gill slit extending to about pectoral-fin ray 11 (Burke 1912). Careproctus gilberti Burke was described from 21 of the 26 syntypes of C. spectrum, and not the presently recognized types of C. spectrum. Schmidt (1950) reported C. phasma from the Sea of Okhotsk based on two specimens. However morphological differences in the illustration provided by Mecklenburg et al. (2002), based on ZIN 29087 and reflecting features described by Schmidt (1950), indicate this species is unlikely to be C. phasma and may be an undescribed species. The pelvic disc is much longer than wide rather than nearly round, the pectoral fin is much longer (ca. 100% HL) than in our material (51.5-86.6% HL), and the rays of the lower pectoral-fin lobe are nearly entirely free. In addition, the collection depth of Schmidt's specimens is 504 m, more than twice as deep as the relatively shallow-water C. phasma from the Bering Sea and Gulf of Alaska.
In the eastern Bering Sea, C. phasma is generally associated with the pool of cold water that extends from the north and in some years reaches the Alaska Peninsula (Stevenson & Lauth 2012). Temperatures recorded at depth during trawls in which C. phasma was caught ranged from -1.7 to 3.4°C (mean 0.3), in contrast with C. scottae, which was captured in temperatures of -1.2 to 4.7°C (mean 2.8). In the Gulf of Alaska, however, C. phasma was collected in temperatures ranging from 4.4 to 7°C; no temperature data was available for collections in the Gulf of Alaska of C. scottae.
In their phylogenetic analysis using cytb and 16s data, Kai et al. (2011a) recovered a clade labeled as ARC1 as sister of the clade BER3 (C. phasma). "UW Uncataloged" was cataloged as UW 154442, a specimen of C. phasma from the northern Gulf of Alaska. Most similar to C. phasma, it differs from by two base pairs from nearly all others and by one base pair from C. lerikimae Lectotype. SU 48, 91 mm, Alaska, north of the Shumagin Islands, between Unga and Nagai islands; 55.167°N, 160.3°W, depth 201 m, Albatross station 2848, 31 July 1888, herein designated (Fig. 4B).
Coloration. The lectotype is now uniform light brown in preservation, with a pale orobranchial cavity, peritoneum, and viscera. The type material was described by Bean (1890) as having "Color along back of some examples light brown, elsewhere uniformly pale." This description is almost certainly of preserved material and likely includes type material of C. gilberti, subsequently described by Burke (1912).  later described a few aspects of coloration in the remaining types of C. spectrum: "Skin transparent, lax; muscles flesh colored; mouth, gill cavity, and internal organs pale; peritoneum silvery, without dots; abdomen silvery." Life history. The largest specimen examined was the lectotype, a 91 mm male (SU 48). Distribution. Careproctus spectrum is known only from the type series taken in the northwestern Gulf of Alaska (Fig. 6). The collection depth was 201 m at the type locality.
Etymology. The specific epithet is derived from the Latin spectrum, meaning "specter" or "ghostly apparition." Remarks. Careproctus spectrum was described by Bean (1890) from the western Gulf of Alaska in the Shumagin Islands, based on at least 26 specimens, apparently split into at least two lots: USNM 45363 and SU 48 (Böhlke 1953;Chernova et al. 2004). Burke (1912) recognized that two species were among the syntypes and subsequently described C. gilberti based on the much smaller disc of many of the specimens. He described C. gilberti on the basis of 25 of the syntypes of C. spectrum, including three specimens of SU 48. A fourth specimen (Fig. 4B) is part of SU 48, labeled with the same tin tag, but was not noted by Burke (1912) and has not been mentioned in later publications. We identified it as likely to be one of the three remaining syntypes of C. spectrum. Unlike the two syntypes of USNM 45363, which are both disintegrating, the condition of this specimen, while poor, is adequate to collect additional morphological data. The apparent designation of USNM 45363 as the lectotype by  is invalid as the lot contains two specimens (Böhlke 1953). Because both of these specimens are in very poor condition, we herein designate SU 48 as the lectoype of C. spectrum and the two specimens of USNM 45363 as paralectotypes. The three specimens of C. gilberti remaining in SU 48 were recataloged as SU 69904.
An original illustration of one syntype is problematic (USNM 45363, view P02535, illustrated by S. F. Denton, provided by L. Palmer, USNM), as it shows an individual with an anus near the anal-fin origin and a dark line along the body. This illustration was published by Mecklenburg et al. (2002) and appropriately modified to place the anus near the pelvic disc following the description of  and to remove the dark line.  Pores of cephalic lateralis system of moderate size, pore pattern 2-5-7-2, chin pores paired. Interorbital pore absent.
Skin relatively thin, loose gelatinous layer beneath skin, short cactus-like prickles uniformly covering body, widely spaced, in most dense region about 10 prickles in orbit length. Pyloric caeca 17-23, length about 33-51 % HL, left side of visceral cavity.
Coloration. Body orangish pink and white to grayish, fins orangish pink in life, with speckling scattered over body and fins (Fig. 3C); head, dorsum from nape to caudal fin, and ventrum at anal-fin origin to caudal fin pink to marginally orange; isthmus, base of pectoral fin, and body posterior of gill slit to anal-fin origin white; belly silvery white (crystalline guanine) to anal-fin origin, black speckling increasing dorsally; dark line internally at base of dorsal fin rays, extending from nape to caudal fin base, and at base of rays in the posterior half of the anal fin; base and lower lobe of pectoral fin white to faintly orange; dorsal margin and distal portion of fin dusky orange; eye with dark dorsal margin, becoming brassy and whiter ventrally. Body and fins pale with speckling in preservation; base of dorsal and anal fins beneath skin with pigment, showing faint line between fins and body; eye entirely black. Peritoneum pale, with occasional scattered speckles dorsally; orobranchial cavity pale; stomach, intestines, and pyloric caeca pale; urogenital papilla pale.
Life history. The largest specimen examined was a 136.2 mm maturing female (UAM 2973). The only ripe female with yolked eggs was 159.0 mm, with eggs about 4.1 mm in diameter. Ripe males ranged from 93 to 132.3 mm.
Distribution. Careproctus lerikimae has been collected only from the Beaufort Sea off northern Alaska (Fig.  6). Collection depths range from 175 to 500 m. One lot in poor condition collected from a haul at a depth of 66 m (Rand & Logerwell 2011) was likely left in the net and washed down from a previous haul conducted at 175 m or deeper (K. Rand, pers. comm., 2014).
Etymology. The new species is named in honor of Erika Acuña, Kim Rand, and Libby Logerwell of the Alaska Fisheries Science Center for collecting or coordinating in 2008 the collection of the first representatives of the new species at sea. The specific epithet is an amalgamation of the collectors' names to be treated as a noun in apposition.
Remarks. Kai et al. (2011a) recovered a clade they identified as "ARC1" that included both Arctic (C. lerikimae; UW 117918) and Gulf of Alaska specimens (C. phasma; UW 154442 as "UW uncataloged") as the sister clade of "BER3" (C. phasma) of the Bering Sea. Within ARC1, C. lerikimae formed the sister group of the single Gulf of Alaska representative of C. phasma, differing from it by 1 bp within cytb data only. New16s and cytb sequence data from C. phasma (UW 151271, 151272, 151291-151296; Table 1) placed the Gulf of Alaska C. phasma well within the C. phasma clade, to the exclusion of C. lerikimae, with 0.2% sequence divergence within C. phasma (Kai, unpublished data, 2014).
Careproctus lerikimae is similar to species of the C. dubius species group of Chernova (2014b) in lacking the postorbital pore and having a long lower pectoral-fin lobe and cactus-like prickles. In contrast, C. lerikimae has a round pupil, unlike the slit pupil of all species in the C. dubius group, and males have a short urogenital papillae (1-2 % SL), unlike the long urogenital papilla (2-6 % SL) in species of C. dubius (Chernova 2005a;Chernova 2014b). In addition, cactus-like prickles are widely spaced over the body in C. lerikimae; all members of the C. dubius species group densely covered by prickles (Chernova 2014ab;Chernova, pers. comm., 2015). Meristic characters are similar, although C. lerikimae has a higher range of vertebral and dorsal-fin ray counts than nearly all species (Chernova 2014b, table 1). However, all but four of the 11 species of the C. dubius group are described from single specimens and thus more complete ranges of morphometric and meristic data are unknown.

Principal component analysis
In the morphometric PCA of western Pacific species, the size component, PC1, accounted for 92.2 % of the variance. Shape components 2, heavily loaded on pelvic disc and lower pectoral-fin lobe lengths, and 3, heavily loaded on lower pectoral-fin lobe and gill slit length, each accounted for 2.4 % of the variance (Table 4). In the meristic PCA, PC1 was heavily loaded on median fin rays and vertebrae, accounting for 71.8 % of the variation, and PC2, heavily loaded on pectoral-fin rays, accounted for 14.4 % of the variation (Table 4). All species clusters in the plot of morphometric PC2 and PC3 overlapped to some degree (Fig. 7A). Careproctus pellucidus was most separated from other species, narrowly overlapping all but the C. acanthodes cluster, from which it was entirely separated. The other three species overlapped broadly. In the meristic PCA, a cluster composed of C. acanthodes and C. pellucidus narrowly overlapped with a cluster comprising C. rastrinus and C. trachysoma (Fig. 7B). In the plots of morphometric PC2 and meristic PC1, C. acanthodes and C. pellucidus were nearly completely separated from each other and from a cluster composed of broadly overlapping C. rastrinus and C. trachysoma (Fig.7C).
In the morphometric PCA of C. lerikimae and similar eastern Pacific species, the size component, PC1, accounted for 90.1 % of the variance. Shape components 2, heavily loaded on lower pectoral-fin lobe length and the fleshy interorbital width, and 3, heavily loaded on the fleshy interorbital width and snout to anal-fin origin length, accounted for 3.0 and 1.7 % of the variance, respectively (Table 4). In the meristic PCA, PC1, heavily loaded on median fin rays and vertebrae, accounted for 66.5 % and PC2, heavily loaded on vertebrae and pectoralfin rays, accounted for 17.3 % of the variation (Table 4). In the plot of morphometric PC2 and PC3, clusters of C. lerikimae and C. phasma broadly overlapped, and C. spectrum was within the C. phasma cluster only (Fig. 8A). In the meristic PCA, clusters composed of C. lerikimae and C. phasma were nearly entirely separated, and C. spectrum again was within the C. phasma cluster near the overlap region (Fig. 8B). In the plots of morphometric PC2 and meristic PC1, C. lerikimae and C. phasma were nearly completely separated from each other and C. spectrum was separate from both (Fig. 8C). 4. Factor loadings for principal components (PC) analysis of morphometric and meristic characters of eastern Pacific and Arctic species of the Careproctus rastrinus species complex lacking a postorbital pore: C. phasma, C. spectrum, and C. lerikimae n. sp.

Discussion
Although members of what we have herein called the C. rastrinus species complex are generally considered either closely related due to their morphological similarity (Kido 1988) or treated as a monophyletic group (Kai et al. 2011a), our morphological evidence suggests they may comprise two or three lineages. One lineage comprises species with a postorbital pore present: C. rastrinus, C. trachysoma, C. scottae, C. pellucidus, and perhaps C. acanthodes. A second lineage includes those in which the pore is absent-C. phasma, C. lerikimae, and, probably, C. spectrum-and may be more closely related to the C. dubius group of Chernova (2014b). Careproctus acanthodes, previously considered synonymous with C. rastrinus (Kido 1988), may be a plesiomorphic member of the lineage containing C. rastrinus or more distantly related. While the postorbital pore is present in C. acanthodes, the upper lobe of the pectoral fin is longer than the lower lobe and all distal radials of the pectoral fin are present as well, unlike all other members of the complex. Until the phylogenetics of the Liparidae and especially Careproctus are better understood, we treat all species as being members of the C. rastrinus species complex.