Parapinnixa affinis Holmes, 1900

Wicksten, Mary K., 2012, Decapod Crustacea of the Californian and Oregonian Zoogeographic Provinces 3371, Zootaxa 3371, pp. 1-307 : 248-249

Parapinnixa affinis Holmes, 1900

( Fig. 56O)

Parapinnixa affinis Holmes, 1900: 95 . — Rathbun 1917: 111. — Schmitt 1921: 255. — Glassell 1933: 321, pls. 20, 21. — Schmitt et al. 1973: 31. — Garth & Abbott 1980: 614, fig. 25.33. — Campos-Gonzalez et al. 1992: 756. — Campos-Gonzalez 2007: 644.

Diagnosis (after Glassell, 1933). Carapace smooth, shining; transversely oval, anterolateral corner dilated, making straight line at anterior margin. Front broad, triangular, with short median groove. Orbit oval, inner hiatus wide, partly filled by basal segment of small, short antenna. Antennule folding obliquely. Buccal area small, broadly triangular. Ischium of third maxilliped rudimentary, merus large, triangular, with 3-segmented palp. Cheliped stout, smooth, hand dilated, dactyl hooked at apex, armed with small tooth near middle of inner margin, upper side smooth; fixed finger with 2 distal teeth, large triangular tooth extending from apex to proximal side of center. Single row setae extending longitudinally from margin of carpus to fixed finger, gape of dactyl with fringe short setae. Pereopod 2 larger than others; dactyl short, stout. Pereopods 3, 4 comparatively slender, with slightly longer dactyls. Pereopod 5 small, reaching about to apex of merus of preceding pair, dactyls short, stout, slightly hooked. Merus of pereopods 3–5 compressed, broad. Abdomen with 7 segments, widest at segment 3, segment 7 nearly twice as long as broad. Carapace length to 3.6 mm long.

Color in life. Carapace light amber with mottling of dark ochre, protogastric, cardiac regions light orange; rarely white. Legs pale ochre with greenish tinge, dactyl yellow with white apex. Setae on pereopods 3, 4 reddish brown (Glassell 1933).

Habitat and depth. Bays and harbors, low intertidal zone among mud, sand, shells, algae; living in tube with polychaetes Amphitrite sp. , Neoleprea californica Moore, 1904 ; and Loimia sp.

Range. San Pedro to San Diego , California ; La Bajada , Tortugas Bay , Baja California, Mexico. Most reports are from Newport Bay, Orange County, California. Reports from Sakhalin and the Kurile Is. may refer to Parapinnixa yokoyai Glassell, 1933 . Type locality Deadmans I., San Pedro, California .

Remarks. Although Glassell (1933) was able to study "hundreds" of this crab, the California bay pea crab has rarely been reported since then. The type locality, Deadmans I., was destroyed during development inside Los Angeles Harbor. Other protected bays of southern California have undergone various types of habitat destruction which probably adversely affected this and other crabs.