> Marlo, I know you like definitive and "accepted" systematics, so maybe
> you'll conform to the WoRMS/Terryn fiat, but there certainly isn't any
> evidence that the later work utilized any criteria other than conchological
> for its generic parsing. Thus there is good reason to hang on to the earlier
> Hastula for the topical species-level taxa.

It's worth bearing in mind that Terryn is responsible for the WoRMS
classification using Terryn's book as the reference, so the two
together constitute one opinion rather than an independent support for
its use.

The DNA paper definitely suggests that more work is needed; of course,
that's true for almost any organism.  Whether a particular group
deserves to have a genus name or not is ultimately a subjective
decision.  Analyses can will tell whether a particular group seems
coherent or not, and we can say that "if A is considered a genus, B is
a similar group and probably should be treated in a similar manner".
But there's no magic amount of difference in DNA, anatomy, or shell
that must or must not be a genus.

--
Dr. David Campbell
Visiting Professor
Department of Natural Sciences
Gardner-Webb University
Boiling Springs NC 28017

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