Ascorhynchus paxillus Child & C. A. 1992

Ascorhynchus paxillum

MATERIAL EXAMINED.—COSTA RICA. Cocos Ridge, E of Isla Cocos, 06°21′N, 85°17′W, 1892 m, coll. R/V Vema, sta V-15-60, 30 Nov 1958, 1 (holotype, USNM 234562) (badly damaged), 1 juv (paratype, USNM 234563).

DESCRIPTION.—Size moderately small for genus; leg span about 16 mm. Trunk (bent, crushed, badly damaged) robust, rather stout in relation to length, fully segmented, posterior of each segment flared into cowl with tiny dorsomedian tubercle. Lateral processes about 1.5 times as long as wide, separated by slightly less than their diameters, armed with 2–3 dorsolateral short setae and tall slender dorsodistal tubercle less than half as long as segment diameter. Ovigers implanted just anterior to bases of first lateral processes. Ocular tubercle low, rounded, eyes small, sensory papillae prominent, tubercle placed at median length of cephalic segment, anterior to oviger implantation. Anterior of cephalic segment with anterolateral tubercles slightly more robust and longer than those of lateral processes, directed anteriorly.

Proboscis (contorted, collapsed) rotund, with proximal hint of suture lines, without distal suture lines. Abdomen fairly short, held little above horizontal, swollen distally, armed with 4–6 short distal setae.

Chelifore scapes 1-segmented, extremely short and small, only as wide as palp bases, as long as 2.5 times their diameters, armed with three setae as long as their diameters. Chelae tiny globular knobs, everted within scape tip, armed with one tiny seta each.

Palps typical, third segment longest, fifth only 0.6 length of third, both armed with few short setae, fifth with 3–4 longer setae, slightly longer than segment diameter. Sixth curved, shorter than seventh, terminal three segments only slightly longer than wide, all armed with fringe of setae of about same length as their segment diameters.

Ovigers also typical, first three segments quite short, fourth and fifth subequal, sixth only 0.7 length of fifth but armed with few very short lateral setae. Strigilis segments each slightly shorter than last, armed with 1–2 ectodistal setae and three rows of endal denticulate spines, two rows of minor or short spines and one row of major or larger spines, major spines in the formula 6:4:4:5, with 3–4 large serrations and several tiny distal serrations per side. Terminal claw very small, only about half length of terminal segment, slender.

Legs slender, lightly setose with few very short setae and several longer dorsal setae measuring 1.5 times segment diameter. First tibiae longest with femorae and second tibiae respectively shorter. Tarsus slightly more than 0.6 length of propodus, both armed with few short endal setae and row of tiny endal sole spines of equal size. Propodus with pair of long ectal spines longer than twice segment diameter. Claw extremely long, longer than tarsus, almost 0.8 propodal length, slender, moderately curved, of equal length on all legs.

Juvenile: Chelae fully formed, fingers without teeth, only slightly larger than adult chelae knobs, ovigers mere buds. Tubercles of trunk middorsum and lateral processes smaller, more pointed.

Male: Unknown.

MEASUREMENTS (holotype, in mm).—Trunk length (chelifore insertion to 4th lateral processes, approximate), 2.29; trunk width (across 2nd lateral processes, approximate), 1.33; proboscis (too badly damaged to measure accurately); abdomen, 0.45; fourth leg, coxa 1, 0.37; coxa 2, 0.64; coxa 3, 0.31; femur, 1.46; tibia 1, 1.63; tibia 2, 1.19; tarsus, 0.46; propodus, 0.74; claw, 0.58.

ETYMOLOGY.—The species name (Latin: paxillus, a peg or small stake) refers to the extremely long propodal claws of this new species.

DISTRIBUTION.—Known only from the type-locality on the Cocos Ridge, east of Isla Cocos, Costa Rica, in 1892 meters.

abyssal