Achelia ovosetosa (Hilton 1942)

Achelia ovosetosa (Hilton)

Ammothea ovosetosa Hilton, 1942g:95.

MATERIAL EXAMINED.—Aleutians, Amchitka Island, Constantine Harbor, on beach, coll. W.H. Dall, sta 305 (1049), 5 Aug 1873 (1, holotype, USNM 81493).

DISTRIBUTION.—Hilton's species is known only from this unique type specimen taken intertidally in the western Aleutian Islands.

DESCRIPTION.—With leg span of about 21.5 mm, species almost twice as large as Hilton's A. megova. Trunk circular in dorsal view, as wide as long, without segmentation sutures. Lateral processes contiguous, armed with low laterodistal swellings bearing groups of very short spines. Cephalic segment anterior rim also bearing groups of short spines. Ocular tubercle a low cone with broad base, a tiny posterior tubercle, and very small slightly pigmented eyes. Abdomen long, carried horizontally and extending beyond first coxae of fourth leg pair, armed with 2 dorsal rows of short spines. Proboscis length subequal to that of trunk, very inflated, barrel-shaped, small oral surface flat.

Chelifore scapes broad, almost cylindrical, only slightly inflated distally, about twice as long as wide, with several short dorsodistal spines. Chela hardly extending beyond scape rim, a semicircle with 1 tiny spine. Palp segments short, very setose distally, distal 4 segments hardly longer than wide, armed with many short setae. Oviger (female) very short, no segment longer than twice its maximum diameter, longer segments with 2–3 tiny distal spines, distal 4 segments with denticulate spines in the formula 0:1:1:2. Spines with many lateral lobes.

Major leg segments short, femur longest with second tibia slightly shorter and first tibia shortest, all segments armed with scattered short spines. Femur inflated, with small conical dorsodistal tubercle bearing 2–3 setae slightly longer than proximal spines. Propodus typical, well curved, heel with 6 spines (4 larger proximal, 2 smaller distally), 12–14 short sole spines. Claw half propodal length, robust, auxiliaries about 0.6 length of main claw.

Male characters unknown.

MEASUREMENTS (in mm).—Trunk length (chelifore insertion to tip 4th lateral processes), 2.02; trunk width (across 2nd lateral processes), 2.02; proboscis length, 1.98; abdomen length, 1.22; third leg, coxa 1, 0.58; coxa 2, 0.74; coxa 3, 0.8; femur, 2.06; tibia 1, 1.74; tibia 2, 1.81; tarsus, 0.25; propodus, 1.14; claw, 0.59.

coastal