Betaeus longidactylus Lockington, 1877

Wicksten, Mary K., 2012, Decapod Crustacea of the Californian and Oregonian Zoogeographic Provinces 3371, Zootaxa 3371, pp. 1-307 : 66

Betaeus longidactylus Lockington, 1877

( Fig. 15 C, D, H, J, L, R, Pl. 3F)

Betaeus longidactylus Lockington, 1877a: 35 . — Rathbun 1904: 108. — Schmitt 1921: 80, pl. 12. — Johnson & Snook 1927: 310, fig. 262. — Hart 1964: 441, figs. 20–22, 27, 32–34, 40–42. — MacGinitie & MacGinitie 1968: 279. — Word & Charwat 1976 b: 55. — Chace & Abbott 1980: 572, fig. 23.5. — Ricketts et al. 1985: 74, fig. 57. — Jensen 1995: 43, fig. 66. — Kuris et al. 2007: 637, pl. 317 F, 317 K.

Alpheus (Betaeus) longidactylus . — Holmes 1900: 190.

Diagnosis. Front of carapace straight, slightly swollen over eye. Stylocerite reaching almost to end of second segment of antennular peduncle. Scaphocerite broad, lateral tooth exceeding blade, reaching nearly to end of antennular peduncle. Carapace without teeth. Pereopods 1 usually similar in size, shape, narrow fingers exceeding palm. In small individuals, no large teeth on inner margin of fingers and no gape between fingers when closed; in large shrimp, teeth, obvious gape can be present. Pereopod 2 with 4 carpal articles, article 1 slightly longer than next three together. Pereopod 3 relatively stout, slightly flattened, with simple dactyl. Pereopods 4, 5 similar to pereopod 3 but smaller, more slender. Abdominal pleura 1–3 rounded, 4, 5 slightly angled. Telson with 2 pairs spines on dorsal surface, 2 spines on each posterolateral angle, posterior margin deeply curved. Total length 40 mm.

Color in life. Olive green, olive brown, red-brown, blue green; with light mid-dorsal stripe; legs reddish with white apices, tail fan dark with yellow setae ( Hart 1964).

Habitat and depth. Tide pools, among eelgrass, on docks, or in burrows of echiuroid worm Urechis caupo Fisher & MacGinitie 1928 ; or mud shrimps ( Upogebia spp. ), intertidal zones. Often found free-living.

Range. Elkhorn Slough , Monterey County, California ; to Tepoca Bay, Gulf of California . Type locality San Diego , California .

Remarks. This tide pool shrimp is common in southern California, and often lives in pairs. It uses its chelipeds to push sediment out of its shallow burrow, and rests under rocks with its chelipeds outstretched in front of it. It is present only on the northern coasts of the Gulf of California. Most records in the Gulf of California come from the vicinity of Puerto Peñasco, Sonora.