Hello,
So finally I hear more about the mystery bivalve I found on our
coast. 2 years ago I went to English Bay beach in Vancouver and
found it packed with the shell you describe. I've seen it other
places since. It is not mentioned in any of the shell books as a
species coming from our area. I had never seen it before, and had
collected shells on many sites in our area: it never used to be in
English Bay. Seems that we have an invader. The once abundant little
pink and white Macoma baltica are almost gone and replaced with
these big purple things.
To answer your question:
The closest thing I have found is Nuttallia nuttallii (Cnrad, 1837)
from California and Baja. My guess is that it either has been
accidentally introduced into BC or is in the process of broadening
its range for other reasons (warming waters?).
Anyone else have information on the pretty but offending beast?
(I haven't looked at my e-mail for a week and haven't looked at the
150+ e-mails waiting yet, so if this is already answered bear with me)



>Can anyone help me with an ID that I thought would be a cinch, but has
>me baffled:
>I collected a number of empty 'butterflied" bivalve pairs from sandy
>beaches on the East Coast of Vancouver Island.
>They are:
>-extremely common on the beaches on which I found them
>-up to about 2" long (at least the ones I found)
>-they look similar to a Macoma as far as I can tell from pictures, most
>like the Chalky Macoma - Macoma calcarea - oval, fairly compressed,
>thin-shelled, muscle scars and pallial sinus similar to drawing in
>Abbott's American Seashells, valves about the same inflatedness,
>periostracum shiny brown to brownish-green, BUT
>the most distinguishing thing about this shell is the strong purple
>colour of the shell, especially inside, most noticeable when wet.  None
>of my books mentions any purple colour in any Macoma or any other shell
>that  can find for this area.  Some other things which are not
>macoma-like as far as indicated in American Seashells, the pallial sinus
>does not differ between valves as far as I can tell, but looks about the
>same in each and there is no posterior twist to the shells that I can
>tell.
>I found a number of associated tiny pairs which I think are the
>juveniles and they often are pale cream well-marked with purple rays.
>Any help from you west-coast experts would be greatly appreciated.
>
>Nora
>Calgary, Alberta
>-no longer on the beach :-(
>
>
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Peter Egerton, Vancouver, Canada
Collector of worldwide Mollusca
http://www.intergate.bc.ca/personal/seashell/index.html
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