Friedrich, 1937
Description:
Body small and thin.
Prostomium semicircular without eyes. Prostomium with 3 antennae and 2 simple palps. Lateral antennae and palps of the same size, with irregular edges and small hairs. Median antenna clearly longer than lateral ones and inserted at the level of the first dorsal tentacular cirri.
3 pairs of simple tentacular cirri on 2 segments.
Dorsal tentacular cirri of first segment as long as the median antenna. Tentacular cirri of second segment a little longer. Parapodia subbiramous. Dorsal and ventral cirri thread-like and simple. Dorsal cirri short at maximum one fourth of palp length and length of lateral antennae. Ventral cirri at most half the size of the dorsal cirri.
Notopodia with 1 acicula and 2 simple chaetae. Neuropodia with 2 aciculae and 4-5 compound chaetae.
Pygidium with 2 thread-like cirri and 2 separate pygidial plates.
Pharynx with 10 terminal papillae, without jaws (H. arenaria-detail).
Size:
Body up to 3.8 mm for 28 segments.
Colour:
Whitish or reddish-brown.
Habitat:
Between sandgrains in low water.
Distribution:
Boreal, antiboreal to tropical world-wide, North Sea.