Northernmost unionids include Margaritifera margaritifera, which
occurs above the Arctic Circle in Scandanavia and northwestern Russia
and various Anodonta s.l. that occur in northwestern Canada, Alaska,
and Siberia.   Pyganodon grandis simpsoniana makes it all the way to
the Arctic Ocean in the Mackenzie River system.  Some sphaeriids also
go far north.

--
Dr. David Campbell
425 Scientific Collections
University of Alabama
"I think of my happy condition, surrounded by acres of clams"

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