(Leach, 1814)
Description:
Body oblong and flattened. Antenna 1 well developed, with a multiarticulate flagellum; antenna 2 very long, longer than the body, with a scale on the outside of the peduncular article 3. Eyes dorsal. Mandible normal, with a strong, truncated molar process. Anterior pereion segments with excavate sides, which, together with the bilobed coxal plates, give the pereion segments 2 and 3 sinuous lateral borders. Pleon of one small, inconspicuous segment, others all fused with the telson to form a large, shield-shaped pleotelson. Postero-lateral borders of pleotelson serrated. Uropods with a peduncle, very long, longer than, or more or less equal in length to, the pleotelson. Adult male with pereiopod 1 normal, subequal to others; preoperculum expanded only slightly at the tip. Coxal plates visible from above on most pereion segments.
Male body length up to 10 mm; females up to 7 mm. Colour yellowish, mottled with red or brown, often with an unpigmented band across the cephalon, anterior to the eyes.
Habitat:
Among sponges, ascidians, coelenterates, polyzoans, Laminaria holdfasts, etc., mainly in dredged material but also between tidemarks.
Distribution:
A subarctic-boreal species most commonly recorded from northern Norway to the Atlantic coast of France, not ranging into the Baltic.