> ----------
> From: Martin S. Kohl[SMTP:[log in to unmask]]
> Sent: vrijdag 12 februari 1999 4:59
> To: [log in to unmask]
> Subject: Corbicula varieties
>
> Hello All;
>
> I've picked up some Corbicula during some recent walks along the Tennessee
> River (yes, it's come to that, Unios are getting so scarce) and noticed
> there
> seems to be two distinct varieties, differentiated by a consistent set of
> characteristics. Variety "2" is more inflated, thicker shelled, has a
> more
> strongly projecting umbo, a more sharply curved posterior corner, and the
> lateral teeth diverge at less than 90°, giving the shell a more strongly
> triangular outline. Variety "1" has the opposite features. The relative
> abundance of the two varies from place to place, but "1" is usually more
> abundant. Intermediate ones are not too common, and I did not see any
> with
> mixed characteristics.
>
> Also, many of the older corroded shells are much larger than the more
> recent
> ones. Does anyone have an opinion on these variations?
>
> Thank you for your interest,
>
> Martin Kohl
>
Also here in the Netherlands there exist two species of recently introduced
Corbicula's, one with relatively broud ribs, called C. fluminea, and a form
with narrow ribs, C. Fluminalis. On the beach you can find fossil
Corbicula's, they don't fit these two newly introduced species. Martin Cadee
(The Netherlands)
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