CALCINUS PASCUENSIS, A NEW FROM EASTER ISLAND (, , ) 1)

BY

JANET HAIG Allan Hancock Foundation, University of Southern California, Los Angeles, California, U.S.A.

The hermit crab described in this paper was collected by Ian E. Efford and Jack A. Mathias during the 1964-65 Medical Expedition to Easter Island and was sent to me by Dr. Efford of the University of British Columbia, Vancouver, B. C. The specimen, the first hermit crab and first anomuran to be reported from Easter Island, proved to belong to an undescribed species of Calcinus (family Diogenidae).

Calcinus pascuensis n. sp. (figs. 1-6) Material examined. - Holotype male, Allan Hancock Foundation Cat. No. 653 ; off Camp Hanga-Roa, Easter Island; in shell of Strombus maculativsNuttall; 28 J,anuary 1965. - Description. Carapace shield longer than broad, the ratio of length to breadth approximately 7/6. Rostrum broad, tip slightly acute and surpassing lateral teeth. Right eyestalk as long as shield, left longer by about half length of cornea; length of right eyestalk 10 times, of left 11 times its minimum diameter. Eyescales wide- set, with a well developed terminal spine and one or two obscure denticulations on distal part of outer margin. Antennular peduncles, when fully extended, reaching distal fourth of shorter eyestalk (a little farther than indicated in fig. 1). Antennal peduncles reaching distal third of shorter eyestalk. Antennal scales extending well past base of third article of peduncle, and armed with strong spines. Antennal scales, and outer margin of carapace shield, with long plumose hairs (not shown in fig. 1 ) ; a few scattered hairs on basal portion of eyestalks. Left cheliped missing. Right cheliped: Merus with two well developed spines, one distal and one submedian, on lower margin of outer surface; three teeth, the median one largest, on lower margin of inner surface. Upper margin of carpus with three strong teeth, the most distal one largest; distal margin of outer surface with a series of corneous-tipped tubercles, the one proximad to the upper margin considerably larger than the others. Palm compressed; upper margin with five subequal, conical teeth, their tips corneous; outer surface with several tubercles disposed as indicated in fig. 2. Upper margin of movable finger with a double

1) Contribution No. 342 from the Allan Hancock Foundation. 28

Figs. 1-6. Calcinus pascuensis n. sp., holotype. 1, carapace; 2, right cheliped, outer surface; 3, right cheliped, inner surface; 4, right pereiopod 2, outer surface; 5, right pereiopod 3, outer surface; 6, right pereiopod 3, inner surface. Hairs not shown in 3, 4, and 6. Scales = 2 mm.