Female: Surface of the genital and postgenital segments are covered in rows of very small spinules.
Male: The 1st exopodal segment of the right P5 with an inner edge spine; the 4th segment with a swollen inner lobe. The fused 2nd and 3rd exopodal segments on the left P5 carry one fine terminal spine and 1 broad truncate spine.
Beaufort Sea, North Pacific, Sea of Okhotsk, Yellow Sea, north and temperate Atlantic, North Sea, English Channel, Baltic Sea
Littoral, coastal, more or less brackish
Female:
The posterior corners of the last thoracic segment are rounded, the head has an obtuse shape. Surface of the genital and postgenital segments are covered in rows of very small spinules. Abdomen contains 4 segments. A1 do not reach the distal edge of the genital segment. P5 one-segmented, is longer than wide, contains an apical and lateral spines and slender spinules only on the distal inner margin of the segment. The apical spine of P5 bulbous at the base, slightly curved, toothed at the inner and outer edge, twice longer than the segment.
Male:
Abdomen contains 6 segments, lacks spinules on the surface. The 1st exopodal segment of the right P5 with an inner edge spine; the 4th segment with a swollen inner lobe. The fused 2nd and 3rd exopodal segments on the left P5 carry one fine terminal spine and 1 broad truncate spine.
A. bifilosa var. intermedia
Abdominal segments naked in males and females, spine of female P5 bulbous at the base. The 1st exopodal segment of the right P5 in males with 2 inner expansions, the 3rd left segment ends with a spine and a small sppendix with 2 spines at its end.
A. bifilosa var. inermis
Abdominal segments without spines. The 1st exopodal segment of the right P5 in males with 2 inner expansions, the last segment narrowed at base. The external spines on the 2nd exopodal segment on the left P5 are grouped.
Broadcast eggs into the water at a rate of 2.4 eggs/day/female. Mean diameter of eggs is 92 um, eggs non sticky.
Female: 0,67-1,25 mm
Male: 0,67-1,25 mm
