>  Congeria leucophaeta

Mytilopsis seems to be a valid genus, applicable to this and other generally (though not exclusively) estuarine dreissinids.  M. sallei is another New World species that has reached the Old World.  Congeria is mostly used for fossils, but a living species, the only cave-dwelling freshwater bivalve I know of, has been reported from the Balkans.

>  Marine molluscs:

Crassostrea virginica has been deliberately introduced to Europe, but I don't know how the population is faring.
Probably many species of teredinids are invasive, but we don't know what was native where before wooden ships spread them around the globe.

I think I recall speculation that Macoma balthica might be a North American species transported to Europe by Vikings.

    Dr. David Campbell
    Old Seashells
    University of Alabama
    Biodiversity & Systematics
    Dept. Biological Sciences
    Box 870345
    Tuscaloosa, AL  35487-0345 USA
    [log in to unmask]

That is Uncle Joe, taken in the masonic regalia of a Grand Exalted Periwinkle of the Mystic Order of Whelks-P.G. Wodehouse, Romance at Droitgate Spa

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