Carapace ornamented with small, rounded fossae in the median area, giving way anteriorly and posteriorly to coarse reticulation with sub-rectangular fossae; sometimes reticulate throughout. Posteroventral fossae tend to form depressed groups in female but not in male. Small, rounded anteroventral and posteroventral protuberances in male but not in female. In dorsal view, greatest width at or behind mid-length, posterior extremity somewhat truncated. Colour buff-brown in living specimens. Male copulatory appendages each with a subtriangular distal process, the apex of the right one being rounded and that of the left one pointed; ejaculatory duct relatively long (H. villosa 15 ).
A common species associated with littoral to shallow sublittoral algae and sediment.
It is widespread around the coasts of Britain and NW Europe. It also occurs in the outer reaches of estuaries, and was found by Horne (1982a) to be an important constituent of the ostracod fauna of an intertidal Sabellaria reef.