Ascorhynchus fusticulus Nakamura, K. & C. A. Child. 1983

Ascorhynchus fusticulum

MATERIAL EXAMINED.—Suruga Bay: Tansei Maru cruise KT69–12, sta 5 (1, holotype, USNM 183805).

DECRIPTION.—Trunk robust, compact oval in outline, fully segmented, with 3 slender median dorsal tubercles. Lateral processes separated by less than their diameters, slightly longer than maximum diameters, without dorsodistal tubercles, but armed with 1 to 5 lateral tubercles each with short spine at tip, in the following order: first lateral processes with 3 posteriorly, second with 3 anterior and 3 posterior, third with 3 to 5 anterior and 2 or 3 posterior, fourth with 1 or 2 anterior and none posterior. Ocular tubercle at anterior of short neck, about 3 times taller than its diameter, rounded at tip, small lightly pigmented eyes placed distally. Proboscis stout, almost 0.66 of trunk length, with 1 proximal constriction, oral surface large, flat. Abdomen moderately long, reaching midlength of second coxae of posterior pair of legs, slightly inflated distally, armed with several short lateral and dorsoposterior setae.

Chelifore scape robust, club-shaped, with slightly papillose surface, armed with few lateral, ventral, and distal setae. Chela tiny, bulbous, inserted within concave scape tip. Fingers atrophied, represented by a slight distal cleft.

Palp 10-segmented, basal 2 segments very short, not as long as wide. Third segment longest, slightly longer than fifth. Fifth armed with several short distal setae and 1 long lateral spine, longer than twice segment diameter. Terminal 5 segments almost equal except tenth, which is slightly longer, each armed with many ventral setae slightly longer than segment diameter.

Oviger 10-segmented, basal segment wider than long, fourth segment longest, slightly longer than fifth, both armed with short endal and ectal setae. Sixth segment half length of fifth, armed with several short lateral and distal setae. Strigilis segments each armed with several lateral and distal setae and endal denticulate spines in the formula 6:4:4:5, spines having 8 or 9 denticulations per side. Terminal claw moderately curved, slender, without serrations, not as long as terminal segment.

Legs slender, moderately short, brachytarsal. Coxa 1 with 2 dorsodistal setae and 2 to 4 short lateral tubercles each with stout spine. Second coxa with very small unarmed genital spur. Third coxa with row of ventral short setae on tiny tubercles. Femur subequal in length to second tibia, both shorter than first tibia, all armed with row of short ventral setae on tiny tubercles. Femur with 2 long dorsodistal spines and several dorsolateral shorter spines. Cement gland a large middorsal sack beneath a raised rectangular tubercle housing the tiny gland pore dorsodistally on posterior 6 legs only. First and second tibiae armed with row of long lateral setae and several dorsal setae of different lengths, some on tubercles, longest setae twice segment diameter. Tarsus short, rectangular, armed with several short ventral spines and 1 dorsodistal seta. Propodus long, slender, almost 4 times length of tarsus, armed with row of short sole spines, without heel or longer heel spines, and bearing several short and long dorsal setae. Claw slender, moderately curved, almost half length of propodus.

MEASUREMENTS OF HOLOTYPE (mm).—Trunk length, 1.92; trunk width, 1.18; proboscis length (laterally), 1.24; abdomen length, 0.69; third leg, coxa 1, 0.35; coxa 2, 0.66; coxa 3, 0.36; femur, 1.22; tibia 1, 1.38; tibia 2, 1.21; tarsus, 0.24; propodus, 0.91; claw, 0.44.

ETYMOLOGY.—The specific name fusticulum is the Latin diminutive of fustis (knotty club or bludgeon) and is in reference to the knotty club-shaped chelifores of this new species.

DISTRIBUTION.—Known only from the type-locality, eastern Suruga Bay, off Izu Peninsula, in 75 to 85 meters.