Betaeus setosus Hart, 1964

Wicksten, Mary K., 2012, Decapod Crustacea of the Californian and Oregonian Zoogeographic Provinces 3371, Zootaxa 3371, pp. 1-307 : 68

Betaeus setosus Hart, 1964

( Fig. 16K–O)

Betaeus setosus Hart, 1964: 455 , figs. 52–53, 57, 68–72, 79, 80, pl. 2. — Kozloff 1974: 165.— Word & Charwat 1976: 59. — Butler 1980: 153. — Chace & Abbott 1980: 569. — Wicksten 1984a: 188. — Ricketts et al. 1985: 408, fig. 312. — Jensen 1986: 180; 1995: 43, fig. 68. — Kuris et al. 2007: 637, pl. 317 H, I.

Diagnosis. Front of carapace deeply indented medially, produced laterally over each eye. Stylocerite reaching nearly to end of second segment of antennular peduncle. Scaphocerite slender, lateral tooth longer than blade, separated from it for nearly 0.5 its length, nearly reaching end of third segment of antennular peduncle. Anterior margin of carapace smoothly curved. Chela of pereopod 1 large, much compressed laterally; fixed finger twice as wide at base as dactyl, which is longer than palm. Left chela with large tooth medially on fixed finger, wide gape, smaller proximal teeth; right chela with slight gape but most of teeth intermeshing. Carpus of pereopod 2 with 5 articles, articles 1, 5 about equal in length, longest. Pereopod 3 with inflated merus bearing large proximal spine, dactyl short, broad, bifid. Pereopods 4, 5 similar but smaller. Pleura of abdominal somites 1–3 rounded, pleura of 4, 5 angled. Telson with 2 pairs dorsal spines, 2 spines at posterolateral angle, posterior margin rounded. Much of body setose. Total length to 25 mm.

Color in life. Variable: nearly white, red, brown or green, matching algae; yellow in light but pink or orange in the dark ( Hart 1964). Specimens from Pillar Point, San Mateo County, California were straw-colored.

Habitat and depth. Among rocks, kelp holdfasts, tide pools, on pilings, among roots of eelgrass ( Zostera sp. ), intertidal zone to 18 m.

Range. Hecate Strait, British Columbia to Morro Bay , California . Type locality Clayoquot Sound, west coast of Vancouver I., British Columbia .

Remarks. Betaeus setosus is invariably associated in Puget Sound with the anomuran crab Pachycheles rudis Stimpson, 1860 (Porcellanidae) , both of which often are found in dead shells of giant barnacles ( Balanus nubilis Darwin, 1854 ) ( Jensen 1986). Individuals observed in California were found in quiet tide pools or in marinas, but were not associated with other invertebrates.