Hi Harry,

Actually I don't have much more to add to the pot than what has been
discussed. The information in Marlo's site is consistent with my view
of the problem, G. granosissima W coast, G. demissa E coast, not sure
about the boundaries or whether species could hybridize. Marlo's
images are absolutely stunning and show well the difference,
especially in shell surface sculpture. We have been using G.
granosissima as a standalone species in the Museum web site since its
inception.

Taehwan and Diarmaid's papers are not focused on Geukensia but on
Brachidontes; however they show, via analyses of two independent gene
groups, that Ischadium recurvum is nested within the two species of
Geukensia. I recall Diarmaid pointing the results to me and commenting
on the strange relationship among these species and how I. recurvum
would actually be a Geukensia.

My apologies for not adding PDFs or URLs of the papers mentioned, but
I had recollections of postings to Conch-L rejected in the past as I
tried to attach URLs or PDFs.

Best wishes,

José

On Tue, Oct 6, 2009 at 5:58 PM, Harry G. Lee <[log in to unmask]> wrote:
> Dear José,
>
> I must admit that the journals you cite aren't on my subscription list, so I
> found .pdf's of the papers (URL's inserted below).
>
> I understand Dr. Ó Foighil was a Bailey-Matthews Shell Museum Visiting
> Curator not long ago. Perhaps you have a better sense of the zoogeography of
> Geukensia demissa and of G. granosissima as a result of that association.
>
> Can you share?
>
> Harry
>
>
> At 06:31 PM 10/6/2009, you wrote:
>
> Actually the molecular work on Geukensia was done partially by Taehwan Lee
> and Diarmaid Ó Foighil (below). They used Ischadium recurvum, Geukensia
> demissa, and G. granosissima as outgroups in molecular studies of species of
> Brachidontes. Both combined (28S and ITS1) nuclear ribosomal (left) and
> mitochondrial COI (right) datasets suggested to these authors that G.
> granosissima is more closely related to Ischadium recurvum than it is to G.
> demissa.  One of the possible interpretation of their results, from the
> taxonomic standpoint, is that Ischadium recurvum could be just another
> species of Geukensia.
>
> Lee, T. and D. Ó Foighil. 2004. Hidden Floridian biodiversity:
> mitochondrial and nuclear gene trees reveal four cryptic species within the
> scorched mussel, Brachidontes exustus, species complex. Molecular Ecology
> 13, 3527­3542 (doi: 10.1111/j.1365-294X.2004.02337.x) <
> http://www.ummz.umich.edu/mollusks/people/diarmaid/leeME2004.pdf >
> Lee, T. and Ó Foighil. 2005. PLACING THE FLORIDIAN MARINE GENETIC
> DISJUNCTION INTO A REGIONAL EVOLUTIONARY CONTEXT USING THE SCORCHED MUSSEL,
> BRACHIDONTES EXUSTUS, SPECIES COMPLEX. Evolution 59(10): 2139­21158 <
> http://www.eeb.lsa.umich.edu/eeb/people/diarmaid/Evolution.pdf >.
>
> Cheers from Sanibel,
>
> José
> ________________________________________________________
> José H. Leal, Ph.D., Director and Curator
> The Bailey-Matthews Shell Museum
> Editor, The Nautilus
> www.shellmuseum.org



--
_______________________________________________________
José H. Leal, Ph.D., Director
The Bailey-Matthews Shell Museum
Editor, The Nautilus
www.shellmuseum.org

3075 Sanibel-Captiva Road
Sanibel, FL 33957 USA
(239)395-2233
fax (239)395-6706

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