LIFE HISTORY AND LARVAL DEVELOPMENT OF CRYPTOLITHODES TYPICUS BRANDT (, ) FROM BRITISH COLUMBIA

BY

JOSEPHINE F. L. HART 410 Queen Anne Heights, Victoria, British Columbia, Canada

The turtle or butterfly crab, Cryptolithode.r typicu.r Brandt, 1849, is a of the order Decapoda, suborder Reptantia, tribe Anomura, and family Lithodidae. It has been found from Unalaska, Alaska, to Monterey, California, to a depth of 2 5 fathoms. This rarely taken form apparently prefers a rocky habitat, where dredging is difficult, and where it is well adapted to escape the notice of collectors in the sub- and inter-tidal zones. When extreme low tides expose its habitat, individuals may be found in rock crevices, or at the base of eel grass, PhylloJPadix sp., where they cling tightly to the substratum by means of sharp, curved claws. The shape and colour of the carapace work together to form an excellent camouflage.

ANATOMY

The name Cryptolithode.r or "hidden stone" applies well to this species, as individuals blend perfectly into the uneven rocky background and they remain in one position without moving for prolonged periods. The common name of turtle crab would appear to be due to the wide lateral expansions of the carapace which entirely cover the appendages when viewed from above or from the sides. The name butterfly probably stems from the shape of the carapace. C. typicu.r has a distinct median crest, rounded dorsally and running from the subrectangular deflexed rostrum to the posterior margin of the carapace. This crest is often of a different colour from the margins and this enhances the 'butter- fly' look. There is some degree of sexual dimorphism shown in the proportions of the carapace and in the size of the chelipeds of the adults. The male carapace is widest at a point more posterior than is found in the female of similar length, and this gives the posterior margin a flatter curve (pl. III). The chelipeds of the male are proportionately larger than those of the female. The first pair of walking legs, or chelipeds, are chelate and have flat teeth on 256 the cutting surfaces. The right is much larger than the left, and the outer surfaces of both have flat tubercles and ridges. The first four pairs of legs each have sharp dorsal crests on all segments and paired ridges on the ventral margins of the meri. The fifth pair of legs is chelate (fig. 11, male), small, and normally kept hidden within the gill chamber. The propodus and dactylus are heavily armed with stiff

Fig. 1. Cryptolithode.rtypicus Brandt. Zoeae I to IV, dorsal view.