In the Roscoff area (Britanny), 57 halacarid species were found in intertidal habitats. The genera present were: Rhombognathus, Isobactrus, Rhombognathides, Metarhombognathus, Actacarus, Halacarus, Halacarellus, Copidognathus, Copidognathides, Anomahalacarus, Coloboceras, Arhodeoporus, Agauopsis, Agaue, Lohmannella, Simognathus and Acaromantis. 13 species are sublittoral, but found in low numbers in the lower and middle part of the tidal belt. In the littoral fringe dominates the genus Isobactrus. The most abundant species are I. hartmanni, I. pulchellus, I. Rugosus and I. Uniscutatus. In the upper eulittoral zone, Rhombognathus procerus, Isobactrus setosus, I. ungulatus, Rhombognathides brevipes, R. merrimani, R. spinipes and Metarhombognathus armatus have their maximum development. In the lower eulittoral zone Rhombognathus notops, R. subtilis, Rhombognathides merrimani and R. seahami are found. In well sorted, medium-sized sediments, the most characteristic species are: Rhombognathus intermedius, Actacarus pygmaeus, Halacarellus capuzinus, H. procerus, Anomahalacarus arenarius, A. intermedius, A. minutus, Acaromantis minutes and the eurytopous Rhombognathides merrimani. In unsorted, rather coarse sands, arenicolous species are rare or absent. Instead eurytopous species are found in great number. In salt marshes the characteristic inhabitants are: Isobactrus uniscutatus, Rhombognathides brevipes, Copidognathus brevirostris and Agauopsis tricuspis. |
