Hi Cecil,
Yes, confusion does continue between the two. I too was grappling with this
about a year ago.
After now having found a few C. gemmatum, the distinctions become obvious
when comparing specimens side by side. The C. gemmatum I've seen are always
brown while C. mundum is typically an off-white (though pure white is not
too unusual). C. mundum has a more solid, heavier shell while C. gemmatum
has a more elongate, thinner, more fragile shell. Hard to describe the
periostracum, though on gemmatum it tends to be a more "hairy" and
concentrated more around each varix. On C. mundum, it tends to be more
bristly, less dense, and more evenly distributed.
C. gemmatum has been much more difficult to find, so my observations for it
are more limitied. Nevertheless, it seems to prefer deeper water, generally
deeper than than 50 ft. C. mundum is much more common, often found
intertidally and usually not deeper than 40 ft.
I suspect you will find both species in French Polynesia though, really, I
don't know. :)
Cheers,
Bob
-----Original Message-----
From: Conchologists List [mailto:[log in to unmask]] On Behalf Of
Cecil Bankston
Sent: Monday, September 26, 2005 12:20 PM
To: [log in to unmask]
Subject: Cymatium gemmatum
Does Cymatium gemmatum occur in the Tuamotus, French Polynesia? Hemming &
Hennen indicate a Western Pacific range; but Coquillages de Polynesie
includes a shell it calls gemmatum. Are shells labeled as being gemmatum
from French Polynesia actually misidentified mundum?
It seems there has been much confusion and contradiction in the literature
regarding gemmatum and mundum, which some authors considered synonyms.
Descriptions of gemmatum say it is tan or brown. Some of the pictured
"gemmatum" on the web are pure white. Are those actually mundum, or are
white gemmatum a common variation?
--
Cecil N. Bankston
Baton Rouge, LA
USA
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