Halacaridae (Acari) von der Atlantikküste des borealen Nordamerikas

Abstract

38 halacarid species from the coasts of the boreal West Atlantic Ocean have been recorded. In a wide-spread net of stations, samples were taken from different substrata in marine and brackish waters in order to obtain information on the biology and ecology of halacarid species. Several habitats with their flora, fauna and halacarid species are described. In intertidal areas on the coasts of boreal North America fewer species were found than known from European coasts. Similar habitats on the west and east coasts of the North Atlantic Ocean are compared with respect to their halacarid population. In the rhombognathine and the genusHalacarellus, most species found in the West Atlantic Ocean are known in the East Atlantic too, living in similar habitats. The generaAnomalohalacarus andCopidognathus are common both in North American and European waters, but comparable biotopes are inhabited by different species, though often related or very similar in their appearance. 45 % of the halacarid species found in the boreal West Atlantic Ocean are also known in the East Atlantic. Hypotheses as to the dispersal and geographical distribution of halacarid genera and species are discussed. It is supposed, that many of the amphiatlantic species invaded biotopes on the American and European coasts, shortly after these continental plates drifted apart.