Harry G. Lee wrote:

> On the other hand, Johnson (1970: 364-365) did not report it in the
> Delaware, Susquehanna, or any of the major river systems of VA. Perhaps
> these systems now support this species, and perhaps this is part of the
> range expansion which occurred between these first two publications.
> This also raises the question of just when and how the species entered
> the Atlantic Drainage in the first place. Could it be after the European
> immigration?
>
> Given this species proven capacity to expand its range by human or other
> agency, as discussed earlier in this thread, is this a foolish question?

* in Ontario, at least, there's also the question of whether it may have
been missed by previous generations of mussellers, because of its muddy
habitat, because the mussellers may have collected mostly in riffles and
lakes. Until recently Utterbackia imbecillis was believed to be
restricted to the Lake Erie drainages of Ontario, but I & others have
found it almost to Quebec, both in direct tributaries of Lake Ontario
and the St Lawrence, but also in the South Nation drainage, which isn't
on such a direct route for introductions.

fred.
------------------------------------------------------------
             Bishops Mills Natural History Centre
           Frederick W. Schueler & Aleta Karstad
        RR#2 Bishops Mills, Ontario, Canada K0G 1T0
     on the Smiths Falls Limestone Plain 44* 52'N 75* 42'W
       (613)258-3107 <bckcdb at istar.ca> http://pinicola.ca
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