(Fig. 36D, Pl. 7E)
Pachycheles rudis Stimpson, 1859: 76, pl. 1, fig. 5. — Holmes 1900: 109. — Rathbun 1904: 168, fig. 6. — Schmitt 1921: 176, pl. 32, fig. 2; fig. 11. — Johnson & Snook 1927: 350, fig. 298. — Haig 1960: 170, pl. 34, fig. 1. — Haig et al. 1970: 26. — Gonor & Gonor 1973: 25. — Haig & Abbott 1980: 589, fig. 24.20. — Hart 1982: 100, fig. 101. — Ricketts et al. 1985: 402, fig. 308. — Jensen 1986: 180; 1995: 74, fig. 147. — Kuris et al. 2007: 648, pl. 326 B1.
Diagnosis. Front narrow, trilobate in frontal view, with dense short setae. Carapace about as broad as long, strongly convex from front to back, mostly punctate or with flattened granules. Chelipeds unequal. Merus rugose, granular, anterior margin with strongly projecting lobe. Carpus with broad subtriangular lobe on anterior margin, dorsal surface covered with long setae, large coarse granules. Chelipeds with large coarse granules; large protuberance at base of dactyl, surface covered with setae which do not extend beyond most proximal part of dactyl. Pereopods 2–4 with thick fringe of plumose setae along anterior margins. Telson with 5 plates. Carapace length to 17.4 mm.
Color in life. Carapace mottled, with gray, brown, white stripes; in smaller animals, may be almost completely white except for one or two brown patches. Chelipeds greenish brown with gray and bluish granules. Pereopods 2–4 mottled with brown, gray, or white The color notes are based on crabs from Pillar Point, San Mateo County, California.
Habitat and depth. Under stones, in holdfasts or in well-protected crevices, usually intertidal, to 29 m.
Range. Kodiak, Alaska to Magdalena Bay, Baja California, Mexico. Type locality Monterey, California.
Remarks. This crab may live in pairs, sometimes in association with the shrimp Betaeus setosus (Jensen 1986).