Allocareproctus tanix Orr & Busby, 2006, new species

Allocareproctus tanix new species

Peach Snailfish

(Figures 1-2, 4-6, 8, 13; Tables 1-4)

Careproctus pycnosoma: Kido 1985:14-16, figs. 3e, 8-9 (HUMZ 88509, Aleutian Island record); Mecklenburg et al. 2002 (after Kido 1985).

Holotype: UW 112294, 65.6 mm, 52.0938ºN, 172.4286ºW, 158 m depth, 4 June 2000, M/ V Dominator, cruise 2000-01, haul 73, benthic bag, J.W. Orr.

Paratypes: UW 112295, 1(45.8 mm), 52.0038ºN, 177.8278ºE, 104 m depth, 11 July 2002, F/V Sea Storm, cruise 2002-01, haul 118, J.W. Orr; UW 113166, 1(63.8 mm, cleared and stained), 53.0785ºN, 170.1512ºW, 183 m depth, 14 June 2004, F/V Gladiator, cruise 2004-01, haul 31, benthic bag, K.P. Maslenikov; HUMZ 88509, 1(77.6 mm), 53.2545ºN, 169.0573ºW, 620 m depth, 19 July 1980, R/V Hatsue Maru No. 62, cruise 1980-01, haul 33.

Diagnosis

Teeth strongly trilobed (Fig. 2B); nasal papilla absent; other pore papillae reduced, invariably present only on maxillary pore 6; peritoneum pale; orobuccal valve with 1 finger-like projection; orobuccal cavity pale; gill rakers 9-10, short, blunt; interorbital papilla absent; pyloric caeca on left side, short; body peach to red; iris golden.

Description

Body relatively deep, depth at pectoral-fin base 17.8-23.0 (23.0)%, at center of pelvic disk 19.5-24.5 (24.5)%, at anal-fin origin 23.3-25.3 (25.3)%. Predorsal relatively long, length 29.0-34.5 (32.9)%. Preanal length 40.6-48.0 (46.8)%.

Head large, width 12.4-16.8 (16.8)%, length 26.3-29.7 (29.7)%. Interorbital width 5.5-6.4 (6.4)%, narrower than orbit length. Snout 7.7-9.2 (8.7)%. Mouth small, maxilla 10.8-12.0 (12.0)%, extending to anterior portion of orbit. Teeth strongly trilobed (Fig. 2B), in a band of 8-9 oblique rows of 9 teeth per row. Orbit large, length 6.4-7.1 (6.6)%.

Papillae present on few pores: absent from nasal pores; variably present on maxillary pores 5-6 (5-6); variably present on preoperculomandibular pores 5-7 (5-7); present on suprabranchial pores 1-2 (Fig. 4C). Papillae unpigmented. Interorbital papilla absent. Cephalic free neuromasts profuse, reduced or nearly indiscernible over interorbit and nape.

Gill opening small, 4.9-7.1 (6.1)%, entirely above pectoral fin or extending to pectoral-fin ray 3 (1). Gill rakers on anterior arch 9-10 (9), blunt and stout. Central projection of orobuccal valve a moderately elongate single lobe.

Dorsal-fin rays 41-42 (41), tips of anterior 4-6 rays projecting from fin membrane, anteriormost rays about 30% free from membrane, succeeding rays less so; posteriormost ray attached membranously to dorsalmost caudal-fin ray for 3.3-6.6 (5.6)%. Anal fin with 34-36 (36) rays, posteriormost ray membranously attached to ventralmost caudal-fin ray for 4.1-6.9 (6.9)%. One or two (2) anal-fin pterygiophores and associated rays anterior to first haemal spine.

Pectoral-fin rays 38-39 (39) in two lobes separated by shallow notch, 10 rays in lower lobe. Dorsalmost ray at level of ventral rim of orbit. Upper lobe rounded, extending to anal-fin origin, length 18.0-20.7 (20.7)%, with ray 8 longest; length of shortest notch ray 9.0 -10.0 (9.6)%; length of lower lobe 16.6-19.9 (17.5)%, extending between posterior margin of pelvic disk to anus, with rays 2-3 (3) longest, rays 4-10 shortening ventrally.

Pelvic disk large, length 9.9-11.6 (10.7)%, width 9.0-11.1 (9.5)%. Distance from disk to anus 4.7-7.6 (4.7)%, about 45-75 (44.3)% DL, distance from anus to anal-fin origin 10.6-15.2 (15.2)%, about 103-143 (143)% DL. Urogenital papilla conical, short, 4.8-17.1 (17.1)% DL, unpigmented. Pyloric caeca 16-21 (16), on left side of body, finger-like, short, 14.4-27.8 (25.6)% HL.

Caudal fin slightly rounded, 14.6-17.4 (17.4)%, depth at hypural plate 3.7-5.2 (5.2)%, with principal rays 12-13 (12), dorsal principal rays 5 (5), ventral principal rays 7-8 (7). Dorsal procurrent rays 2-3 (2), borne on epural and posteriormost neural spine; ventral procurrent ray 1, borne on expanded posteriormost haemal spine. Vertebrae 45- 47 (47), abdominal vertebrae 9-10 (10), caudal vertebrae 35-37 (37).

Body in life peach to red; iris golden. Color in alcohol pale, with pigment absent from cephalic papillae and at origin of dorsal fin. Peritoneum pale; orobranchial cavity pale.

Largest specimen examined a 77.6 mm female (HUMZ 88509). Smallest female with yolked eggs 77.6 mm; smallest male with enlarged, swollen testes 63.8 mm.

Range

Allocareproctus tanix has been found only in the eastern and central Aleutian Islands, from off Kiska, Seguam, and Umnak Islands, at depths of 104-620 m (Fig. 8).

Etymology

The specific epithet is derived from the Aleut word “tanix” for “forehead” in reference to the absence of nasal papillae on the pale head. It is to be treated as a noun in apposition.

Remarks

We collected three of the four specimens known and all were a distinctive peach coloration, unlike the red color of other species of Allocareproctus. Kido (1985) described the fourth specimen, which he identified as C. pycnosoma, as being red in life. This difference in coloration may be a reflection of the much greater depth at which his specimen was obtained (620 m, in contrast to the 104-183 m depth of our material).

Comparisons

Allocareproctus tanix can be distinguished from other species of Allocareproctus by its pale peritoneum, in contrast to the black peritoneum of all other species. It is further distinguished from A. jordani and A. kallaion by its strongly trilobed teeth and fewer cephalic pores with papillae, and from A. unangas by the absence of an interorbital papilla. Only A. kallaion can be distinguished from A. tanix using meristic characters; these characters include numbers of abdominal vertebrae and gill rakers (Table 2), which also distinguish A. kallaion from all other Allocareproctus. Several morphometric characters differ among A. tanix and other species of Allocareproctus, primarily a reflection of the deeper body of A. tanix. In A. kallaion, head length, body depth at anal-fin origin, upper and lower suborbital depth, predorsal length, snout to pelvic length, and pelvic disk length and width are less than in A. tanix. In A. jordani, the several morphometric characters discussed above are less than in A. tanix, and in A. unangas, suborbital depth to the mandible is less than in A. tanix.