Ascorhynchus okai Nakamura & Child 1983

Ascorhynchus okai

MATERIAL EXAMINED.—Suruga Bay: Tansei Maru cruise KT69-12, sta 5 (1, hototype, USNM 183806).

DESCRIPTION.—Holotype small, leg span about 13 mm. Trunk elongate, with small slender median dorsal tubercles. Lateral processes less than twice as long as their diameters, separated by distances slightly greater than their diameters, armed with tiny dorsodistal tubercles not taller than wide. Ocular tubercle large, situated toward anterior of cephalic segment, slightly taller than its diameter, capped with slender tubercle shorter than ocular tubercle diameter at eyes. Eyes large, darkly pigmented. Proboscis almost as long as trunk, with single proximal constriction, lips only slightly protruding from flat oral surface. Abdomen long, reaching almost to middle of second coxae of posterior pair of legs, armed with several dorsolateral setae.

Chelifore short, inflated. Scape 1-segmented, armed with several lateral setae. Chela small, rounded, without trace of fingers.

Palp 10-segmented, basal 2 segments short, first slightly longer than wide, second shorter than its diameter. Third segment longest, slightly longer than fifth. Third through fifth armed with several dorsal and lateral setae, fifth with single long dorsal seta. Terminal five segments consecutively shorter, each only slightly longer than its diameter, armed with many ventral setae longer than segment diameter.

Oviger 10-segmented. First segment short, second and third longer, subequal in length, fourth almost as long as fifth, the longest segment. Second through fifth segments armed with pair of short recurved spines, fifth with few distal setae. Sixth segment armed with few short lateral setae and several longer distal setae. Strigilis four segments armed with 2 or 3 dorsal setae and 2 rows of denticulate endal spines in the formula 5 : 4 : 3 : 4, for the row of larger spines, and 6 : 4 : 3: 2, for the row of smaller spines. Larger spines with 4 or 5 pairs of serrations; smaller spines, less than half the size of the larger with single pair of laterodistal serrations. Terminal claw slender, well curved, slightly longer than terminal segment, unarmed.

Legs slender, moderately long, brachytarsal. Second coxa with few dorsolateral setae and 2 or 3 ventrodistal setae. Femur with a row of lateral setae and few dorsal and ventral setae. Single cement gland on median dorsal surface, consisting of subcuticular gland capped by single distal- pointing small truncate cone. Tibiae armed with row of short and long setae, several long dorsal setae and several short ventral setae; long setae twice as long as segment diameter or slightly longer. Tibia 1 the longest segment, tibia 2 only slightly shorter. Tarsus slender, rectangular, slightly over 0.3 propodal length, armed with 4 or 5 ventral spines as long as segment diameter and 2 lateral setae and 1 dorsal seta. Propodus slightly curved, armed with 7 or 8 sole spines of equal length, few lateral setae and 10 or 11 dorsal and distal setae, some longer than twice segment diameter. Claw robust, well curved, slightly over half propodal length.

MEASUREMENT OF HOLOTYPE (mm).—Trunk length, 1.3; trunk width, 0.87; proboscis length, 1.18; abdomen length, 0.48; third leg, coxa 1, 0.27; coxa 2, 0.51; coxa 3, 0.32; femur, 1.14; tibia 1, 1.39; tibia 2, 1.26; tarsus, 0.21; propodus, 0.58; claw, 0.3.

ETYMOLOGY.—Named for Dr. Hidemiti Oka, professor emeritus of Tokyo Kyoiku University and former director of the Shimoda Marine Biological Station, Tokyo Kyoiku University.

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

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