Andrew,
Thanks for the great info on Epitoniidae. This kind of e-mail
is why am a CONCH-L member! The more we share our knowlege and
views with each other, the more we all benifit in our hobby.
I have a great love for taxonomy and evolution, and the idea
of genus vs subgenus has always been a bit of an enigma to me.
It's all very subjective and so changes in thinking are constant.
Peter Egerton
Vancouver, BC, Canada


>In shell morphology "Epitonium" blainei is identical to Cirsotrema
>zelebori. The latter, as stated in my message of 30-7-99, is the
>evolutionary end-member of an unbroken fossil lineage (I have numerous
>specimens of this lineage at hand). Its oldest-known direct ancestor is C.
>lyratum, which spans a timerange from at least the middle Eocene to the
>late Miocene. C. lyratum is highly variable, with some specimens closely
>resembling the type species of the genus, C. varicosum, with lamellose
>costal crests in or nearly in contact with one another and largely hiding
>the shell surface underneath. If "E" blainei is indistinguishable from a
>member of this lineage, how then can it belong in another genus?
>
>The only way in which "E" greenlandicum differs from Cirsotrema is by the
>smooth surface of its costae. However specimens of C. zelebori from the
>southern end of its range in New Zealand also have smooth costae. The
>spiral sculpture is similar in all of the abovementioned species, as well
>as other species from the Atlantic, Japan and elsewhere, from the late
>Cretaceous to Recent. Costae of Cirsotrema may be fused solid or loosely
>lamellose, and this can vary intraspecifically.
>
>"E" greenlandicum, as with most other Cirsotrema, differs from Epitonium in
>its spiral sculpture of strong cords overlain by finer lirae, and by a
>heavy symmetrical peribasal cord. This type of sculpture is unknown in
>Epitonium.
>
>I can see no reason not to consider Boreoscala an outright synonym of
>Cirsotrema. Merely because Boreoscala has traditionally been considered a
>subgenus of Epitonium does not mean it is cast in stone.
>
>Now to throw a real can of worms into the ring (throw your arms up in
>horror! Who is this character Grebneff?) When you look at the whole
>morphological range of Cirsotrema, Amaea, Boreoscala and all of the
>subgenera of Epitonium, it is impossible to sort them neatly into
>consistent groupings. They all overlap, sometimes more than two "genera" at
>a time. Where does Epitonium end and Parviscala (=Asperiscala) begin? Where
>does Parviscala end and Amaea begin (and is Filiscala is a Parviscala or an
>Amaea without a peribasal cord)? Where does Amaea end and Cirsotrema begin?
>The answer is that they don't "end", they all blend into one another. And
>the "line" they form bends back and touches itself at some points ie it
>forms a sort of irregular net rather than a line. What is Gyroscala? Is it
>an Epitonium with a peribasal cord? How can Gyroscala be used, when
>presence of the cord is inconsistent within a species? Sure, there are
>species "typical" of these so-called genera/subgenera, but as a whole the
>thing just doesn't work. I think when eventually (hint, hint) cladistic and
>DNA work etc is done, there will be big changes. My feeling is that this
>whole grouping will eventually be shown to be congeneric. And such
>subgenera as Nitidiscala, Hialoscala, Hirtoscala, Mazescala etc have no
>basis in reality. I leave all this with individual Ep nuts to think about.
>
>It is important to be as objective as possible in taxonomy. Just because an
>author says "IT IS SO" does not necessarily mean that it is so, and a new
>revision is not automatically accurate. When we really WANT something to be
>THIS way we are quite capable of throwing objectivity away in order to
>force the evidence to fit our preferences. This is particularly the case
>with a large and difficult group of relatively featureless shells such as
>Epitoniinae (though far more so with such as Eulimidae. Look what Anders
>Waren has managed to do with that family. Perhaps we need him to examine
>the Epitoniidae). But we must always remember that any taxonomic decision,
>by anyone, is always an OPINION. (This is not an attack on anyone, please
>note. It is merely my own personal opinion).
>
>Regards
>Andrew Grebneff
>
>
Peter Egerton, Vancouver, Canada
Collector of worldwide Mollusca