Ammothea dorsiplicata (Hilton 1943)

Ammothea dorsiplicata (Hilton)

Leionymphon dorsiplicatum Hilton, 1942:97–98. [New combination.]

MATERIAL EXAMINED.—CHILE. Northwest of Valdivia, 38°08′S, 75°53′W, 1238 m, coll. U.S. Fisheries Steamer Albatross, sta 2791, 14 Feb 1888, 1 (holotype, USNM 81524), 14 chelate juv (paratypes, USNM 81525).

Other Material: Same locality and station, 1, 10 chelate juv [not listed and presumably not seen by Hilton].

DESCRIPTION.—Size large, leg span over 12 cm. Trunk completely segmented, integument covered with closely spaced microsetae. Lateral processes separated by slightly less than their diameters, without adornment. First through third trunk segments with swollen transverse ridges each bearing a tall dorsomedian tubercle, almost as tall as ocular tubercle. Ocular tubercle more than twice as tall as minimum diameter, constricted near base, swollen and rounded distally. Eyes slightly pigmented, anterior pair twice as large as posterior pair. Abdomen long, straight, carried almost horizontally, extending slightly beyond tips of first coxae of posterior leg pair, slightly swollen distally.

Proboscis cylindrical, less than half trunk length, rounded distally with slightly protruding lips.

Chelifores small, short scape constricted medially, vestigial chela small, carried at ventral oblique angle.

Palp 9-segmented, longer than proboscis, segments slender, second and fourth slightly less than five times longer than their maximum diameters. Fourth segment subequal to first, terminal five segments of reduced diameter, subequal in their lengths, each armed with few short ventral setae.

Oviger 10-segmented, distal segments increasingly setose to seventh, with terminal three segments palp-like with few short setae. Fifth segment longest, sixth well curved, armed with many distal short setae, seventh shorter, with many ectal short setae. Eighth segment placed anaxially on seventh, ninth anaxial to eighth, tenth very slender, subequal in length to ninth.

Legs very long, slender, major segments armed with longitudinal rows of short lateral setae and fringe of tiny distal setae. Second tibiae the longest, femorae slightly longer than first tibiae. Cement gland dorsodistal on femur with single small oval pore about one segment diameter proximal to femur tip, pore at integument surface, not on raised tubercle or swelling. Tarsus very short, semicircular, armed with few short dorsal and ventral setae and two very small ventral spines. Propodus short, moderately curved, without marked heel, sole with three large heel spines each increasingly larger than one more proximal. Distal sole with row of 15–18 small spines. Claw robust, half propodus length, slightly curved, auxiliaries very slender, only about 0.35 length of main claw. Anterior two pairs of propodi slightly shorter and thicker than posterior two pairs. Sole and heel spines and claws identical on all propodi.

Female: Measurements slightly greater except for oviger which is smaller, shorter, with fewer setae per segment. Each segment decreases in diameter from the next proximal one. Legs with propodi having four heel spines. Propodi of posterior four legs markedly more slender and with more sole spines than anterior four. Genital pores on all eight second coxae.

MEASUREMENTS (holotype, in mm).—Trunk length (chelifore insertion to tip 4th lateral processes), 11.0; trunk width (across 2nd laterel processes), 6.2; proboscis length, 5.2; abdomen length, 4.5; third leg, coxa 1, 2.3; coxa 2, 4.3; coxa 3, 2.9; femur, 14.8; tibia 1, 14.6; tibia 2, 15.8; tarsus, 0.8; propodus, 3.6; claw, 1.8.

DISTRIBUTION.—Known only from the type-locality, northwest of Valdivia, Chile, in 1238 meters.

bathyal