One difficulty, however, is that the modern diversity of arcids is
still not thoroughly sampled for genetic or detailed anatomical and
shell data.  Many of the existing genetic studies use different genes,
making comparisons difficult, and some of the popular genes such as
cox1, aka COI, don't generally give good resolution for divergences as
old as some of the splits within Arcoida.  Thus, there may be
additional names out there, currently treated as synonyms, that would
be a more appropriate name for candida.

However, Barbatia as used in the 1969 Treatise on Invertebrate
Paleontology and followed by Abbott (1974), etc. is based pretty much
on "has a byssal gape and isn't Arca".  That's not very restrictive,
and it shouldn't be surprising if more then one group of ark shells
fits that description.


On Thu, Nov 8, 2012 at 4:32 PM, Harry Lee <[log in to unmask]> wrote:
> Marlo, Les, Trish, David and other Listers:
>
> I think the first step in answering Les's question is to define the genera
> in competition for assignment of Arca candida Helbling, 1779:
>
> Barbatia Gray, 1842 Type species: Arca barbata Linnaeus, 1758, a Recent
> Mediterranean species, by original designation (Gray, 1842: 81). See
> <
> http://www.conchology.be/?t=68&u=243201&g=1bbb9fdc1e9384262153cf0e3f48c4af&q=6348919dfdd22cd7dbccce37da11fb96
>>.
> Cucullaearca Conrad, 1865 <
> http://www.biodiversitylibrary.org/item/54552#page/25/mode/1up> Type
> species: Byssoarca lima Conrad, 1847 [no figure;* 2 syntypes Invert. Paleo.
> ANSP 30642:
> <
> http://clade.ansp.org/invert_paleo/collections/index.php?mode=search&anspnumber=30642&taxonname=&country=&state=&strat=&geologicage=&operator=%3D&submit=Perform+Search
>>]; see <
> http://books.google.com/books?id=r_mY7_V5GE4C&pg=PA295&lpg=PA295&dq=Byssoarca+lima&source=bl&ots=3XxlWhP5e0&sig=40UampvW7WNxYqAp0jJD3HSLQ8I&hl=en&sa=X&ei=afybUMiXLoTq9ATL5oGICA&sqi=2&ved=0CC4Q6AEwAA#v=onepage&q=Byssoarca%20lima&f=false
>> of the Lower Oligocene, Vicksburg Group, MS by subsequent designation
> (Stoliczka, 1871: 340
> < http://www.biodiversitylibrary.org/item/110955#page/384/mode/1up>)
>
> Arca candida was assigned to Barbatia early on, and those workers who saw
> affinities with Cucullaearca placed it in Barbatia (Cucullaearca) for many
> years as well - including Garvie (1996: 28
> < http://www.biodiversitylibrary.org/item/91585#page/28/mode/1up>), who
> described Cucullaearca as "elongate to obliquely subquadrate, subequal but
> generally much distorted, ventral valve margin deeply sinuated by a large
> byssal gape [my boldface]; cardinal area high, amphidetic; sculpture formed
> by fine to coarse subequal costae; hinge long, straight, teeth in continuous
> series in young, in adults divided in the middle by large gape, distal teeth
> conspicuously larger and oblique" and gave its range as Upper Cretaceous to
> Recent (warm seas).
>
> Using mitocondrial DNA sequences, Marko (2002: see p. 2009 at <
> http://mbe.oxfordjournals.org/content/19/11/2005.full.pdf+html>) presented
> evidence that (Recent) Cucullaearca, conchological affinities
> notwithstanding, was only distantly related to Barbatia. I think this work
> was the basis for Bieler and Mikkelsen (2004: 510), Oliver and Holmes
> (2006), Mikkelsen & Bieler (2008: 52) and a few others** removing
> Cucullaearca from Barbatia and affording it full generic rank. I know it was
> why I did so (Lee, 2009: 19; species 31).
>
> This splitting trend is not unanimous; Coan and Valentich-Scott (2012) cite
> Marko's work but summarily synonymize Cucullaearca with Barbatia !
>
> * but figured a couple of months later at <
> http://www.biodiversitylibrary.org/item/110628#page/393/mode/1up >
> **  I lost my Huber (2010) to the elements a few months ago, so I cannot
> report on his treatment
>
> Bieler, R., and P.M. Mikkelsen. 2004. Marine bivalves of the Florida Keys: a
> qualitative  faunal analysis based on original collections, museum holdings
> and literature data. Malacologia, 46(2): 503-544.
> Coan, E.V. and P. Valentich-Scott, 2012. Bivalve seashells of tropical West
> America: Marine bivalve mollusks from Baja California to Northern Peru, Part
> 1 & 2.  Santa Barbara Museum of Natural History Monographs, 6. Santa Barbara
> Museum of Natural History: Santa Barbara, CA. xv + (1)-1258.
> Garvie, C.L., 1996. The molluscan fauna of the Reklaw Formation, Marquez
> Member (Eocene: Lower Claibornian), in Texas. Bulletins of American
> Paleontology 111(352):1-140.
> Gray, J.E., 1842. Mollusca (pp. 48-92) in Synopsis of the Contents of the
> British Museum 44th edition. British Museum, London. Pp. 1-304.
> Huber, M., 2010. Compendium of bivalves. A full-color guide to 3,300 of the
> world’s marine bivalves. A status on Bivalvia after 250 years of research.
> ConchBooks, Hackenheim, Germany. 901 pp.
> Lee, H.G., 2009. Marine shells of northeast Florida. Jacksonville Shell
> Club, Inc., Jacksonville, FL. 204 pp. + 19 color pls. May 28.
> Marko, P.B., 2002. Fossil calibration of molecular clocks and the divergence
> times of geminate species pairs separated by the Isthmus of Panama.
> Molecular Biology and Evolution 19: 2005–2021.
> Mikkelsen, P.M., and R. Bieler, 2008. Seashells of Southern Florida: Living
> Marine Mollusks of the Florida Keys and Adjacent Regions. Bivalves.
> Princeton University Press, Princeton, NJ. 503 pp.
> Oliver, P.G. and A.M. Holmes, 2006. The  Arcoidea (Mollusca: Bivalvia): a
> review of the current phenetic-based systematics. Journal of the Linnean
> Society 148: 237-251.
> Stoliczka, F., 1870-1871. Cretaceous fauna of southern India (cont'd) vol.
> 3. The Pelecypoda with a review of all known genera of this Class, fossil
> and Recent. Geological Survey of India, Memoirs, Paleontologica Indica Parts
> 1-4: xxii + 1-222 + plates 1-12 (1870) Parts 5-13: 223- 537 + plates 13-50
> (1871).
>
> Harry
>
>
>
> At 04:19 AM 11/8/2012, you wrote:
>
> Can anyone help with a reference???????
>
> Marlo
> From: Leslie A. Crnkovic
> Sent: Monday, November 05, 2012
>
> Any idea as to why C. candita [sic] was moved to another genus? … i.e. -
> from Barbatia to Cucullaearca?
> Les
>
> From: Marlo Krisberg
>
> Sent: Monday, November 05, 2012
>
> Here are two more Ark shells from Florida. < Cucullaearca candida (Helbling,
> 1779)>



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

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