Pachygrapsus crassipe

Wicksten, Mary K., 2012, Decapod Crustacea of the Californian and Oregonian Zoogeographic Provinces 3371, Zootaxa 3371, pp. 1-307 : 263

Pachygrapsus crassipe s Randall, 1840

( Fig. 61A, Pl. 15E)

Pachygrapsus crassipes Randall, 1840: 125 , pl. 5, fig. 4. — Holmes 1900: 79. — Rathbun 1904: 189; 1917: 241, pl. 59. — Weymouth 1910: 61, pl. 13, fig. 41. — Schmitt 1921: 270, text fig. 159, pl. 45. — Johnson & Snook 1927: 395, figs. 354, 355. — Garth & Abbott 1980: 619, fig. 25.43. — Ricketts et al. 1985: 42, fig. 27. — Jensen 1995: 17, fig. 3. — Kuris et al. 2007: 641.

Diagnosis. Carapace nearly square, lateral margins broadest behind orbit, entirely upper surface except cardiac, intestinal regions transversely grooved, sides with single tooth posterior to prominent postorbital tooth. Third maxillipeds with merus lobate at antero-internal angle. Chela of adult male broad, heavy; raised line present on upper side of propodus, smaller line on lower portion of outer surface, apice of fingers spooned. Female chela not as broad as in male. Merus of pereopods 2–5 broad, with tooth on posterodistal angle except on pereopod 5; propodus, dactyl of each leg spinulose. Male carapace length 41 mm, female smaller.

Color in life. Carapace dark green with faint whitish stripes, inner surface of chela white, adult male chela bright red above, white below. The color notes are from crabs from Moss Beach, San Mateo County, California .

Habitat and depth. Upper intertidal rocks, sometimes on docks, pilings or mud flats.

Range. Japan, Korea; Charleston, Oregon to Santa Margarita I. and Alijos Rocks, Pacific coast of Baja California; sporadic in Gulf of California. Type locality "Sandwich Islands", but probably in error. Most of Randall's specimens came from California, especially near Monterey, Los Angeles, and San Diego .

Remarks. Pachygrapsus crassipes is one of the most common crabs of California and Oregon. The megalops larvae can ride on drifting seaweed or wood, giving the species great capacity for dispersal. The population in Asia may have been introduced in ballast water from ships.