Jaera albifrons

Leach, 1814

Body narrowly oval in females; males smaller than females and broadest across the posterior pereion segments. Lateral margins of both sexes fairly sparsely fringed with spines. Antenna 1 very small with a reduced flagellum; antenna 2 well developed but shorter than the body. Eyes large and situated laterally, particularly in males. Mandible with a strong, truncated molar process. Coxal plates of pereion segments not visible from above. Pereiopods of male 1 to 5 normal, 6 and 7 having the distal region of the carpus extended as a lobe which is fringed with less than 15 spines. Pleon of one small, inconspicuous segment, others all fused with the telson to form a large, shield-shaped pleotelson. Pleotelson posterior border fairly deeply excavate where uropods are inserted. Uropods terminal, small, much shorter than the pleotelson and barely projecting beyond the pleotelson notch in which they are set. In females the first pair of pleopods absent, second forming a plate-like operculum covering the remaining pleopods. Preoperculum of male T-shaped with only slight lateral extensions to each arm of the T.
Males up to 2.4 mm body length; females up to 5.0 mm. Colour grey patterned with black in various colour varieties.

Most common at HWN on sheltered shores, often in estuaries and usually beneath stones in areas which retain surface water at low tide.

Widespread in the north-east Atlantic from the French coast northwards to Arctic waters.