Oregonia gracilis Dana, 1851

Wicksten, Mary K., 2012, Decapod Crustacea of the Californian and Oregonian Zoogeographic Provinces 3371, Zootaxa 3371, pp. 1-307 : 219

Oregonia gracilis Dana, 1851

( Fig. 50G)

Oregonia gracilis Dana, 1851: 270 . — Holmes 1900: 19. — Rathbun 1904: 171; 1925: 71, pls. 24, 25, text figs. 19, 20. — Schmitt 1921: 198, text figs. 122a, b. — Johnson & Snook 1927: 365, fig. 315. — Garth 1958: 136, pl. I, fig. 2, pl. 10, pl. 11, fig. 1. — Hart 1982: 176, fig. 69. — Ricketts et al. 1985: 298, 334. — Jensen 1995: 20. — Komai & Yakovlev 2000: 309, fig. 2 (extensive synonymy). — Kuris et al. 2007: 641.

Diagnosis. Rostrum with two long, slender contiguous spines, length, shape of rostral spines variable; and rows of hooked setae. Carapace subtriangular, setose, covered by prominences, broader in female than male. Prominence on anterior side of eye peduncle. Postorbital spine remote from eye, acute, directed outward. Septum between first antennae produced into spine. Chelipeds of male robust, those of female more slender, exceeding length of pereopods 2–5, merus subcylindrical, tuberculate; carpus rounded, hand long, slender; fingers slender, smooth, incurved. Pereopods 2–5 cylindrical, decreasing in length posteriorly, dactyls long, tipped by claws. Male carapace length 65.7 mm, width 39 mm; female 27.5–44.6 mm, width 165 mm.

Color in life. Tan or gray, red mark on chela ( Garth 1958).

Habitat and depth. Among algae, eel grass and pilings, intertidal zone to 390 m but usually subtidal in California and Oregon .

Range. Off Choshi, Chiba Prefecture, Japan to Comander Is.; Bristol Bay , Bering Sea to Monterey Bay, California; rarely found south of Point Arena, California. Type locality Puget Sound, Washington .

Remarks. Oregonia gracilis decorates heavily with bits of algae, hydroids, bryozoans, sponges and wood chips. Komai & Yakovlev (2000) noted that there are two morphs of this species, one with long chelipeds and pereopods 2–5 and the other with short chelipeds and pereopods 2–5 but with longitudinal rows of long stiff setae on the propodi of those pereopods. The two morphs occur sympatrically and thus are considered to belong to the same species. These authors also note that there is considerable sexual dimorphism in the species. Females have relatively shorter rostral spines and more dense setae on the dorsal surface of the carapace than do the males, as well as differing in the shape of the abdomen and the chelipeds.