Alpheopsis equidactylus (Lockington, 1877)

Wicksten, Mary K., 2012, Decapod Crustacea of the Californian and Oregonian Zoogeographic Provinces 3371, Zootaxa 3371, pp. 1-307 : 59

Alpheopsis equidactylus (Lockington, 1877)

( Fig. 14 A)

Alpheus equidactylus Lockington, 1877a: 35 . — Holmes 1900: 187; pl. 3, figs. 45–46. — Rathbun 1904: 10.

Crangon equidactylus . — Schmitt 1921: 76, fig. 53. — Johnson & Snook 1927: 309.

Alpheopsis equidactylus . — Word & Charwat 1976: 37. — Wicksten 1984a: 186; 1994: 120. — Chace 1988: 4.

Diagnosis. Front trispinose, rostrum narrow, shorter than first segment of antennular peduncle. Ocular teeth acute, shorter than rostrum. Stylocerite reaching end of second segment of antennular peduncle. Scaphocerite with broad blade, lateral tooth exceeding blade. Basicerite with small tooth on dorsal margin, 1 small outer lateral tooth, large basolateral tooth. Carpocerite exceeding blade of scaphocerite. Carapace with posterolateral notch. Pereopods 1 similar in size, shape. Chela with transverse groove extending along upper edge almost to posterior margin, dactyl closing vertically. propodus with 2 teeth on cutting edge. Carpus of pereopod 2 with 5 articles, article 1 as long as next 4 combined. Pereopods 3–5 slender, with long dactyls; 1–2 small spines on ischium of pereopods 3, 4. Pleura of abdominal somites 1–4 rounded, those of 5, 6 pointed. Telson with 2 pairs dorsolateral, one pair long terminal spines. Total length 19.1 mm.

Color in life. Carapace and abdomen with broad red stripes, appendages red to orange, telson and uropods translucent with broad red stripe distal to articulation with abdomen. The color is based on a photograph of a shrimp at Redondo Beach, California.

Habitat and depth. Sand and mud, subtidal to 85 m.

Range. Monterey to Cortez Bank, California. Type locality Monterey , California .

Remarks. Schmitt (1921: 77) mentioned that "according to Coutière" this is Alpheopsis trispinosus Stimpson, 1860 . Alpheopsis trispinosus ranges from New South Wales to Tasmania ( Banner & Banner 1973). Chace (1988: 4) stated that A. equidactylus might "be distinct" from A. trispinosus but did not compare material from the two species. Alpheopsis trispinosus has a broader rostrum than does A. equidactylus . The carpocerite of A. trispinosus does not extend beyond the scaphocerite. The basicerite of A. trispinosus lacks a small tooth between the upper margin and the larger lower tooth. There are two small teeth on the dactyl of the major chela as well as a large one in adult A. trispinosus . Pereopod 3 dactyl is relatively shorter in A. trispinosus than in A. equidactylus .

The original description of A. equidactylus was not accompanied by illustrations. The only previous illustration of this species is a crude line drawing of the chela by Holmes (1900) without the characteristic dorsal notch. Figure 14A shows the gross anatomy of the species but not the setae, spines or other fine details of the appendages and telson.