>Dear all,
>
>I've always had a hang-up about that. I guess I have a tendency to
>be a lumper since I can't handle all the complexity. But I believe
>that it is generally accepted as a sign of species differentiation
>since there are many muricids that differ only in the protoconch. Is
>there any scientific agreement on the subject?

If eggs from a single capsule can yield both types of protoconch,
this makes nonsense of UNCRITICAL (careless) use of protoconch
morphology in taxonomy. Separation by type is fine PROVIDED it is
KNOWN that that a brood from that species will all be of one type; if
this is not known (as in most cases, I'm sure) it is risky to make
assumptions.

Also a species can over time change from one type to another, which
could explain how species with nonplanktotrophic protoconchs today
are found in isolated noncontinental oceanic islands (Fiji, Hawaii
etc), where deep water is an absolute barrier to dispersal, and where
low sealevel and plate tectonics cannot be used to ecxplain their
presence there.

Some folk won't even place a gastropod in an ORDER unless he can
examine the protoconch (Klaus Bandel). This is going overboard.

Some groups however sort well by protoconch type; the Triphoroidea
(Cerithiopsidae, Cerithiellidae, Triphoridae) are a good example.
--
Andrew Grebneff
165 Evans St, Dunedin 9001, New Zealand
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