(Milne-Edwards, 1830)
Description:
Body smooth and laterally flattened ; coxal plate 1 not produced forwards, plates 2 to 5 rounded, posterodistal margins with a few long setae; epimeral plates 1 to 3 rounded. Lateral lobes of head broadly rounded; eyes moderately large, rounded. Antenna 1 much longer than antenna 2, about half the body length, peduncle short with article 1 robust and slightly longer than article 2, article 3 very small, flagellum long and slender, up to 30-articulate. Antenna 2 peduncle articles 4 and 5 about equal in length, flagellum quite short, setose, up to 15-articulate. Gnathopod 1 small, basis with a small anterodistal lobe, propodus rectangular, setose, palm transverse, convex, dactylus much longer than the palm. Female gnathopod 2 similar to gnathopod 1 except that it is slightly larger and with the carpal lobe more slender. Male gnathopod 2 extremely large, carpus very short, propodus massive, elongate, palm extending the entire posterior margin, sparsely setose, with a large tubercle close to the base of the dactylus, palmar margin minutely crenulate, dactylus massive reaching the entire length of the propodus, with the inner margin sinuous and setulose. Pereiopods 3 and 4 merus expanded; pereiopod 5 basis very broadly expanded; pereiopods 6 and 7 basis with only a narrow posterior lobe, propodus only weakly expanded distally. Uropods 1 and 2 spinose, outer ramus slightly longer than the inner one; uropod 3 outer ramus with the dorsal margin finely toothed and with two strong apical hooks, inner ramus with one or two apical spines and several setae; uropod 3 peduncle inner distal margin with four or five short spines, outer distal margin with a group of long setae. Telson short, broad, apex truncated between lateral cusps.
Size:
Up to 10 mm.
Colour:
Greenish yellow, or yellowish with red markings.
Habitat:
Intertidal and in the shallow subtidal on algae; also described as epipelagic since it is often cast up with Sargassum along parts of the American coastline.
Distribution:
North Atlantic, American and European coasts; a southerly species ranging from the Sargasso Sea to western Norway.