(Fig. 26B–D)
Pandalus montagui tridens Rathbun, 1902a: 901; 1904: 41. — Schmitt 1921: 42, pl. 13, fig. 2. — Kozloff 1974: 163. — Word & Charwat 1976: 185.
Pandalus tridens. — Butler 1980: 137, pl. 8B (extensive discussion of nomenclature). — Wicksten 1989b: 313. — Jensen 1995: 55, fig. 104.
Diagnosis. Body moderately stout, shell thin, surface smooth. Length of rostrum 1.3–1.8 times carapace length, distal half slightly ascending, with 9–13 dorsal spines, teeth; 6–8 ventral teeth; no dorsal teeth on distal half, apex bifid or trifid. Carapace with pterygostomian, antennal teeth. Eyes large. First antenna with short stylocerite, length of flagella extending beyond rostrum by about 0.3 times their lengths. Second antenna with scaphocerite reaching middle of rostrum, scaphocerite narrow with lateral tooth slightly exceeding blade, basicerite with weak lower tooth, flagellum longer than body. Third maxilliped with slight lamina on antepenultimate segment, epipod present. Pereopods 1–4 with epipods. Pereopod 1 chelate. Pereopods 2 unequal, left longer with about 74 carpal articles; right shorter with 20–28 articles. Pereopods 3–5 with 5–7 spinules on dactyl, propodus with 15–32 spinules, carpus with 2–4 spines, merus with 4–7 spines, ischium with 0–1 spine, decreasing in number from pereopod 3–5. Posterior margin of abdominal somite 3 with moderate projection. Pleuron of somite 4 with weak ventral point, posterolateral margin of somite 5 with strong point. Somite 6 shorter than telson. Telson with 5 pair dorsolateral spines. Male total length to 83 mm, female to 123 mm.
Color in life. Fine red dots over translucent backgroun. Red blotches, bands on pereopods, yellow blotches on pereopods 3–5, third maxilliped with yellow apex. Antennal flagellum with alternate red, transparent bands, flagella of first antenna with red, white bands (Butler 1980, color plate 8B).
Habitat and depth. Rocky areas, 5–1984 m.
Range. Cape Oyutorsky, Pribilof Is. to San Nicolas I., California, but few records south of Washington state. Type locality off North Head, Akutan I., Alaska.
Remarks. Pandalus tridens has been caught commercially off British Columbia. It has been reported southwest of the Colombia River (McCauley 1972, as P. montagui tridens) and off Point Arena and San Nicolas I. in California (Schmitt 1921). Most recent records are from Puget Sound northward.