GRAPSOIDEA MacLeay, 1838

Wicksten, Mary K., 2012, Decapod Crustacea of the Californian and Oregonian Zoogeographic Provinces 3371, Zootaxa 3371, pp. 1-307 : 262

SUPERFAMILY GRAPSOIDEA MacLeay, 1838

The shore crabs (families Grapsidae and Varunidae ) inhabit intertidal regions or floating objects. Recent molecular studies ( Schubart et al. 2002) tend to validate the elevation of what were considered to be subfamilies by Rathbun (1917) to the level of full families. Fast moving and hardy, they are conspicuous inhabitants of temperate and tropical regions worldwide. Their eyestalks are not as long as those of the Ocypodidae , but their vision apparently is keen. They usually are scavengers and grazers on algae instead of deposit feeders. They do not construct long burrows, as do the Ocypodidae . The crabs often are sexually dimorphic, with the male being larger and more brightly colored than the female.

Except for the smallest crabs, which tend to be translucent to drab, the grapsoid crabs of California and Oregon have characteristic color patterns. A rare color form, in which the carapace is either entirely china white to yellowish or patched with these colors, and pereopods 2–5 are banded, occurs in both species of Hemigrapsus .

Three species of grapsoids are common in intertidal areas of California and Oregon. Another two species rarely occur on floating objects, and may be cast ashore after severe storms. Holmes (1900: 84) described yet another grapsoid, Grapsodius eximius , from San Diego, California. This crab resembled a species of Pachygrapsus , but had the posterior surface of the orbits "bulging outwards.” The species was not illustrated, and the type material seems to have been lost. The crab has not been reported since its description. It may have been an aberrant specimen of a species of Pachygrapsus . A record of Pachygrapsus transversus ( Gibbes, 1850) from California ( Schmitt 1921: 271, fig. 160) probably is in error. The species ranges from the southern Gulf of California south to Peru.