Hi Marlo,
Many authors working with large numbers of specimens and species of marine
and fossil gastropods do count the nucleus. Look in Hansen (1980), Jablonski
& Lutz (1980; 1983), Maes (1983), Shuto (1974), Taylor (1975), and Leal
(1991), to cite a few. Using their methodology, the starting line in
Verduin's drawing (the "zero" line) would be tallied already as 0.5 whorl.
That being said, I believe that, no matter the methodology used, it is
important that it should be clearly defined. Anyone can then translate the
work in question into their preferred system.
Hansen, T. 1980. Influence of larval dispersal and geographic distribution
on species longevity in neogastropods. Paleobiology 6: 193-207.
Jablonski, D. & R.A. Lutz. 1980. Molluscan larval shell morphology -
ecological and paleontological applications. In: D.C. Rhoads & R.A. Lutz
(eds.) Skeletal Growth of Aquatic Organisms. Plenum Press, New York, pp.
322-377.
Jablonski, D. & R.A. Lutz. 1983. Larval ecology of marine benthic
invertebrates. Biological Reviews 58: 21-89.
Leal, J.H. 1991. Marine prosobranch gastropods from oceanic islands off
Brazil; species composition and biogeography. Universal Book Services,
Oeestgest, The Netherlands, 418 pp.
Maes, V.O. 1983. Observations on the systematics and biology of a turrid
assemblage in the British Virgin Islands. Bulletin of Marine Science 33:
305-335.
Shuto, T. 1974. Larval ecology of prosobranch gastropods and its bearing on
biogeography and paleontology. Lethaia 7: 239-256.
Taylor, J.B. 1975. Planktonic prosobranch veligers of Kaneohe Bay, 606 pp.
Unpublished PhD dissertation, University of Hawaii.
Cheers from ultra-rainy Sanibel,
José
________________________________________________________
José H. Leal, Ph.D., Director and Curator
The Bailey-Matthews Shell Museum
Editor, The Nautilus
www.shellmuseum.org <http://www.shellmuseum.org/>
3075 Sanibel-Captiva Road
Sanibel, FL 33957 USA
(239)395-2233
fax (239)395-6706
P Please consider the environment before printing this e-mail
From: Conchologists List [mailto:[log in to unmask]] On Behalf Of
marlo krisberg
Sent: Thursday, February 04, 2010 1:58 PM
To: [log in to unmask]
Subject: [CONCH-L] Counting protoconch whorls
Counting protoconch whorls on spiral-helico gastropods has always left me
uncertain. Seems I usually count about 1/4 to 1/2 more than what others
describe. So, I've asked others how they do it and found there is indeed
more than one choice. The method described by Verduin (1977) seems to be
used by many. This method defines a portion of the protoconch as the
nucleus and does not include the nucleus in the count of protoconch whorls.
I've always included the nucleus in my counts. Go to this link to see
illustration of the Verduin method.
http://z14.invisionfree.com/Conchologist_Forum/index.php?showtopic=1889
So, my questions are:
What do you do?
Is there a "correct" way?
Why not count the nucleus?
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