Nieuwe en minder bekende vlokreeftjes van sublitorale harde bodems in het Deltagebied (Crustacea: Amphipoda: Gammaridea)

New and lesser-known amphipods of hard substrates in the Delta area of the Netherlands (Crustacea: Amphipoda: Gammaridea) The distribution of 27 new and lesser-known amphipod species of sublittoral hard substrates in the Delta area in the southwest of The Netherlands is described. Data from literature on these species are scarce and/or not readily available. They are supplemented with results from recent investigations of mainly sublittoral hard substrates. Of the 22 marine species only nine occur offshore as well as inshore. The others seem to be restricted to inshore man-made coastline protections. This probably reflects the scarcity of hard substrates further offshore. Four invasive species were recorded in the brackish and freshwater part of the Delta area, two of them of pontocaspian origin.