Allocareproctus Pitruk & Fedorov 1993

James Wilder Orr & Morgan Scott Busby, 2006, Revision of the snailfish genus Allocareproctus Pitruk & Fedorov (Teleostei: Liparidae), with descriptions of four new species from the Aleutian Islands., Zootaxa 1173, pp. 1-37 : 4-14

Allocareproctus Pitruk & Fedorov 1993

Figures 1-13; Tables 1-4

Type species: Careproctus jordani Burke , by original designation of Pitruk & Fedorov (1993).

Comparative material examined

Careproctus attenuatus ,

USNM 74386, ca. 32 mm, Aleutian Islands, S of Agattu I., 52.24ºN, 174.22ºE, 882 m depth, 7 June 1906, R/V Alabatross, sta. 4781 (poor condition);

Careproctus opisthotremus ,

USNM 74385, 39.8 mm, Aleutian Islands, S of Agattu I., 52.02ºN, 174.65ºE, 1913 m depth, 7 June 1906, R/V Albatross, sta. 4780;

Careproctus ectenes ,

USNM 48618, ca. 50 mm, and USNM 53031, ca. 50 mm, Aleutian Islands, N of Unalaska I., 54.03ºN, 166.81ºW, 640 m depth, 21 August 1890, R/V Albatross, sta. 3331 (poor condition);

Careproctus pycnosoma ,

USNM 73340, 39 mm, Kuril Islands, off Simushir I., 46.7ºN 151.75ºE, 419 m depth, 24 June 1906, R/V Albatross, sta. 4803;

Careproctus curilanus ,

USNM 73341, 64 mm, Kuril Islands, off Simushir I., 46.7ºN, 151.75ºE, 419 m depth, 24 June 1906, R/V Albatross, sta. 4803;

Careproctus candidus ,

USNM 74384, holotype, 60.7 mm, and USNM 74527, paratypes, 2(57-63 mm), 52.93ºN, 173.43ºE, 247 m depth, R/V Albatross, sta. 4784, off Attu I., 11 June 1906;

Lopholiparis flerxi ,

UW 47868, 32.5 mm, holotype, Aleutian Islands, off Ulak Island, 51.4593ºN, 178.4612ºW, 285 m depth, F/V Vesteraalen, cruise 2000-01, haul 120, 20 June 2000, W.C. Flerx;

Prognatholiparis ptychomandibularis ,

UW 42431, 88 mm, holotype, Aleutian Islands, Seguam Pass, 52.3184ºN, 172.7453ºW, 455 m depth, 22 June 1997, F/V Vesteraalen, cruise 2000-01, haul 58, W.C. Flerx.

Diagnosis

Small papillae present on some pores of cephalic lateralis system (Figs. 3-4); nasal pores 2, maxillary pores 6, preoperculomandibular pores 7, suprabranchial pores 2 (pore pattern 2-6-7-2; Fig. 4A); symplectic extending to medial aspect of quadrate and metapterygoid (Fig. 5); tips of anterior 4-8 dorsal-fin rays extending beyond dorsal-fin membrane (Fig. 3); pelvic disk large, 30-45% HL; gill slit small, entirely above pectoral fin; nare single; pseudobranch absent; pectoral radials 4 (3+1), robust, notched, interradial fenestrae three (Fig. 6); pupil of eye round.

Description

Body moderately robust, cylindrical in cross section, nearly uniform in depth from anterior to posterior, tapering slightly posteriorly. Head moderately large, dorsal profile gradually sloping from nape to snout. Snout rounded, slightly projecting beyond upper jaw. Mouth small, maxilla extending to midorbit, oral cleft to anterior rim of orbit. Lower jaw terminal, premaxillary tooth plates matching mandibular tooth plates. Premaxillary teeth simple to trilobed in 8-10 oblique rows, increasing from 3 teeth anteriomedially to 16 teeth posterolaterally. Mandibular teeth simple to trilobed in 9-12 oblique rows, increasing from 4-6 teeth per inner row to 34 teeth in outer row. Diastema absent at symphysis of upper and lower jaws. Orbit large, about 20-32% HL, dorsal margin excluded from dorsal contour of head, suborbital depth to oral cleft 20-60% orbit length; pupil round. Interorbital space wide, slightly convex. Snout slightly longer than orbit, 25-36% HL. Branchiostegal rays 6. Nare single, in well-developed tube at level with upper part of orbit; nostril tube length 2.0-11.0% HL.

Cephalic lateralis pores of moderate size: nasal pores 2, maxillary pores 6, preoperculomandibular pores 7, suprabranchial pores 2 (pore pattern 2-6-7-2; Fig. 4); papillae on rim of some pores; chin pores paired in separate pits. Interorbital (= coronal of Pitruk & Fedorov 1993) pore absent; interorbital papilla present or absent. Cephalic free neuromasts relatively large and profuse or nearly indiscernible. Free neuromasts (Andriashev & Stein 1998) about 15, small and difficult to discern, originating from above gill slit and extending to a level at mid-body above anal-fin origin. Gill opening small, 15-30% HL, upper margin at level of dorsal rim of orbit to just above pectoral fin or extending to pectoral-fin ray 1-3. Opercular flap rounded or angular. Pseudobranch absent. Branchiostegal rays 6. Sympletic expanded posterodorsally, overlapping ventral part of metapterygoid and posteroventral portion of quadrate blade (Fig. 5).

Dorsal-fin rays 39-45 (Table 1), tips of anterior 4-8 rays projecting from fin membrane, anterior 5 rays uniserial and unsegmented, more posterior rays biserial and segmented; all rays simple. Anteriormost dorsal-fin ray supported by two pterygiophores; the anteriormost inserted between neural spines 2 and 3. Anal-fin rays 33-39 (Table 1), anterior ray uniserial and unsegmented, more posterior rays biserial and segmented; all rays simple. One to three anal-fin pterygiophores and associated rays anterior to first haemal spine; posteriormost 2 neural and haemal spines without associated dorsal- and anal-fin rays. Anal-fin origin below vertebrae 10-13 (caudal vertebrae 1-3).

Pectoral-fin rays 33-42 (Table 1). Pectoral fin shallowly notched (Figs. 2, 5), with upper lobe of 24-33 rays extending to about anal-fin origin, dorsalmost rays lengthening to rays 5-7, more ventral rays gradually shortening to shortest ray of notch; lower lobe moderate, with 8-10 rays, extending to between pelvic disk and anus or slightly posterior, dorsal rays gradually lengthening to rays 3-4, more ventral rays gradually shortening to ventralmost ray near pectoral symphysis. Tips of rays 6-20% 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 area between ventral rim of orbit and maxilla. Lowermost pectoral-fin ray below posterior rim of orbit or slightly posterior to posterior rim. Pectoral radiais 4 (3+1), robust, notched. Interradial fenestrae three (Fig. 6).

Pelvic disk large, 30-45% HL, round, slightly wider than long, anterior lobe well developed, flat with margins often slightly upturned. Anus closer to pelvic disk than to anal-fin origin. Principal caudal fin rays 11-14 (Table 1), dorsal procurrent rays 1-3, ventral procurrent rays 1-2. Posterior dorsal-fin rays overlapping caudal fin 15-40% CL; posterior anal-fin rays, 20-50% CL. Skin thin, fragile, prickles absent. Pyloric caeca thick, length about 15-50% HL.

Vertebrae 45-50, 9-12 precaudal, 33-40 caudal (Table 2). Pleural ribs present on vertebrae 8-10, long and slender. Hypural plate composed of dorsal and ventral plates, divided by deep split about 75% length of plate. Epurals 1-2.

Body pale, red to orange, with darker anterior portions in some species (Fig. 1). Peritoneum and orobranchial cavity pale or black; stomach, intestines, pyloric caeca, and urogenital papilla pale.

Range

The genus Allocareproctus has been collected from Sagami Bay, Japan, the Kuril Islands, the eastern Sea of Okhotsk (Vinnikov & Novikov 2004), southern Kamchatka (Sheiko & Fedorov 2000; Tokranov 2000), the Aleutian Islands from Kiska Island to the Islands of Four Mountains, and to just south of the Pribilof Islands in the southeastern Bering Sea (Figs. 7-11). The species range in depths from 75 to 621 m.

Etymology

“Allo” from the Greek “αλλο”, meaning “other”, and “ Careproctus ”, from the Greek “кαρα”, meaning “head”, and “πρωκτος”, meaning “anus” (Pitruk & Fedorov 1993).

Comparisons

Pitruk & Fedorov (1993) suggested the similarity of Pseudonotoliparis and Temnocora to Allocareproctus based on elongate anterior rays of the dorsal fin. In the illustration and original description of Pseudonotoliparis , however, the anterior dorsal-fin rays appear to be only slightly exserted from the membrane, similar to many species of liparids but dissimilar to Allocareproctus . In Temnocora , the anterior rays form a small lobe in which the tips are slightly free from the membrane, similar to that of Lopholiparis flerxi (Orr 2004) and undescribed species of Careproctus from the Aleutians (Orr in prep.). This condition is also unlike that of the anterior rays of Allocareproctus , which gradually lengthen from anterior to posterior and are up to 50% free of the membrane in the anteriormost rays. We identified the first lot of Allocareproctus from the Aleutians in a collection that also contained the holotype of Prognatholiparis ptychomandibularis Orr & Busby . Prognatholiparis is similar in general body morphology and body color but is readily distinguished by its lack of exserted dorsal-fin rays, and presence of a protruding lower jaw and strong folds around the cephalic pores on the jaws. All of these genera lack the papillae found in all species of Allocareproctus .

Several other species have been compared with and considered allied to A. jordani , and thus Allocareproctus , by Kido (1985, 1988). These include Careproctus pycnosoma Gilbert & Burke , C. curilanus Gilbert & Burke , C. ectenes Gilbert , and C.attenuatus Gilbert & Burke . All lack papillae on the cephalic pores. Although the types of these species are small (39-64 mm) and are probably juveniles, even our smallest specimens of Allocareproctus (40.3-60.0 mm) possess well-developed papillae.

Among these species, C. pycnosoma is most similar to Allocareproctus , and based on our examination of Kido’s (1985) material, his C. pycnosoma (HUMZ 88509) represents one of our new species described below. As well as lacking papillae, the holotype of C. pycnosoma has a more slender body than all species of Allocareproctus . While the head and body shapes of C. pycnosoma are somewhat similar to Allocareproctus , both C. ectenes and C. curilanus have strongly protruding snouts and attenuate bodies, with much higher median fin and vertebral counts than in all species of Allocareproctus . The anterior dorsal-fin rays of C. pycnosoma and C. curilanus were originally described as exserted (Gilbert & Burke 1912), similar to the condition in Allocareproctus . Although the condition of the holotypes of these species is good for their age, the membranes of the dorsal fin are damaged, and therefore we are unable to assess their original condition. In C. ectenes , the anterior rays are exserted, yet differ in that dorsal-fin rays 2-3 are longer than the other rays; in adults these anterior rays develop into an elongate anterior lobe. The holotype and only known specimen of C. attenuatus (Mecklenburg et al. 2002) is in poor condition and at least the anteriormost three dorsal-fin rays are missing. The fourth ray is proportionally the same length indicated in the illustration of the holotype (about 30% HL, Gilbert & Burke 1912). Only three other liparids in two genera possess cephalic papillae or barbels (Kido, 1985): Odontoliparis ferox Stein , Rhinoliparis attenuatus Burke , and R. barbulifer Gilbert . All these species lack a pelvic disk and are thus apparently unrelated to Allocareproctus , and in both genera, the papillae are different from the condition in Allocareproctus . In Odontoliparis , the papillae are large and robust on the midline of the snout and between maxillary and mandibular pores (Stein 1978), unlike the small papillae of Allocareproctus that are found on pore margins. Smaller papillae are also scattered “in no discernible pattern” over the head in Odontoliparis (Stein 1978:34). In Rhinoliparis , the barbels around the mouth are long and not directly associated with pores.

Key to species of Allocareproctus

1A. Teeth trilobed, nearly all with moderate to strong lateral lobes; peritoneum pale or dark; nasal papilla present and unpigmented or absent ................................................. 2

1B. Teeth simple, often with weak shoulders; peritoneum dark; nasal papilla present, pigmented ...................................................................................................................... 4

2 A. Peritoneum pale; nasal papilla absent; interorbital papilla absent; Aleutian Islands: Kiska Island to the Islands of Four Mountains ................... Allocareproctus tanix n. sp.

2B. Peritoneum dark; nasal papilla present or absent; interorbital papilla present or absent ....................................................................................................................................... 3

3A. Nasal papilla absent; anal-fin rays 36-39; interorbital papilla present; papillae on maxillary pores 5-6 or 6 only; Aleutian Islands: Buldir Island to the Islands of Four Mountains ............................................................. Allocareproctus unangas n. sp.

3B. Nasal papilla present; anal-fin rays 33-35; interorbital papilla present or absent; papillae on maxillary pores 4-6 or more; Aleutian Islands: Seguam Island to the Islands of Four Mountains ................................................................. Allocareproctus ungak n. sp.

4A. Orobuccal cavity dark; orobuccal valve with 4-6 finger-like projections; gill rakers 14-18; abdominal vertebrae 12; anterior part of body dark; interorbital papilla absent; Aleutian Islands: Seguam Island to the Islands of Four Mountains ................................ ........................................................................................ Allocareproctus kallaion n. sp.

4B. Orobuccal cavity pale; orobuccal valve with 1 finger-like projection; gill rakers 8-12; abdominal vertebrae 10-12; anterior part of body pale; interorbital papilla present or absent; Aleutian, Pribilof, and Kuril Islands; Japan ..... Allocareproctus jordani (Burke)