Crangon alaskensis Lockington, 1877

Wicksten, Mary K., 2012, Decapod Crustacea of the Californian and Oregonian Zoogeographic Provinces 3371, Zootaxa 3371, pp. 1-307 : 110

Crangon alaskensis Lockington, 1877

( Fig. 27C, D)

Crangon alaskensis Lockington, 1877a: 34 . — Zarenkov 1965: 1763. — Kozloff 1974: 164. — Butler 1980: 108. — Carvacho

& Olson 1984: 65. — Jensen 1995: 40, fig. 59. — Kuris et al. 2007: 636, pl. 319 F. Crangon alaskensis elongata Rathbun 1902a: 888 ; 1904: 115, fig. 54. Crago alaskensis elongata . — Schmitt 1921: 88, fig. 58. — Johnson & Snook 1927: 313. — Word & Charwat 1976: 73. —

Wicksten 1980c: 362. Crago alaskensis .— MacGinitie & MacGinitie 1968: 274.

Diagnosis. Exoskeleton thin and smooth. Rostrum reaching or exceeding cornea of eye, apex rounded. Carapace with 1 median dorsal tooth, also hepatic, branchiostegal teeth, moderate pterygostomian tooth. Eye pigmented. Stylocerite acute, about as long as first segment of antennular peduncle. Scaphocerite narrow, lateral tooth much longer than blade, blade tapering toward distal end. Third maxilliped setose, with exopod. Pereopod 1 with inner spine, strong distal spine on merus, propodus broad, dactyl closing obliquely against propodus. Pereopod 2 slender, chelate. Pereopod 3 slender, with simple dactyl. Pereopods 4, 5 longer and more robust than third, with simple dactyls. Pleura of abdominal somites rounded or blunt. Abdominal somite 6 with posterolateral tooth, ventral groove. Telson with 2 pairs dorsolateral spines, about as long as uropods. Male total length 52 mm, female 65 mm.

Color in life. Grayish brown with scattered black spots.

Habitat and depth. Fine sand, euryhaline, intertidal zone to 275 m but usually subtidal.

Range. Bering Sea to Todos Santos Bay , Baja California . Type locality Mutiny Bay , Alaska .

Remarks. Rathbun (1902) distinguished a southern form, C. alaskensis elongata , on the basis of having a longer rostrum and scaphocerite than specimens from Alaska. Considerable overlap has been noted in these characters among shrimps from British Columbia ( Butler 1980). I examined 100 specimens from off San Diego, California. In these, shrimps with a carapace length of 7 mm or less often had a broader width/length ratio of the palm of the subchela, about 0.5 instead of 0.3. The rostrum in some of these smaller shrimps from off San Diego was short and broad, not reaching the end of the cornea of the eye. Regardless of the size of the individual, the rostrum usually was more or less level with the plane of the carapace, but in 3 individuals, the rostrum rose at about a 30˚ angle relative to the carapace. Males had a more slender body than adult females. There was little variation in the relative lengths of the scaphocerite, telson and uropods from that mentioned by Butler (1980); therefore, I concur with his suggestion that designation of the form C. alaskensis elongata as a distinct subspecies be dropped from the nomenclature.

Holmes (1900: 170) considered C. alaskensis to be a synonym of C. nigricauda , but the two species are distinct in morphology and habitat. A narrow scaphocerite with a long, acute lateral tooth is characteristic of the former, which usually occurs in deeper waters than the latter species.