Dear Conch-lers,

If you ever wondered about what to do with those flat, whitish slipper
shells from the East Coast, there is hope now. Rachel Collin from the
University of Chicago/Field Museum of Natural History just published a very
thorough study of the Crepidula plana species complex occurring from
western Texas to New England (Collin, R. 2000. Phylogeny of the Crepidula
plana [Gastropoda: Calyptraeidae] cryptic species complex in North America.
Canadian Journal of Zoology 78: 1500-1514). Using several independent
techniques including DNA sequencing, scanning electron microscopy of shell
and soft parts, and observation of early development stages, she has shown
that there are three shallow-water cryptic (very similar, particularly in
shell morphology) species. Crepidula plana Say, 1822, ranges from (at
least) New England to Georgia. Crepidula depressa Say, 1822, ranges from
Lake Worth, Florida, (possibly a little further north of this) to Port
Aransas, Texas (possibly westward into Mexico). And then there is the newly
described Crepidula atrasolea Collin, 2000, occurring from Core Sound,
North Carolina, to Sanibel, Florida (the type locality fo C. atrasolea is
Wulfert Point, on the northern, bay side of the island). Although is should
still be difficult to ID shells only (minus soft parts), the job is now
made much easier in the presence of soft parts. Crepidula atrasolea has
darker foot and mantle pigmentation. The other two species have
lighter-colored soft parts, and their ranges are apparently mutually
exclusive. Other differences are in radular morphology, type of
development, protoconch, reproductive anatomy, and DNA structure.

Cheers,

José
__________________________________________________________________________
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
(941)395-2233; fax (941)395-6706