Maurizio:
 
I guess since no one has replied, although I am days behind in reading my
email, I will take my crack at your questions:
 
At 12:21 PM 3/20/99 +0100, you wrote:
>Saturday    March 20, 1999   11:46 AM
>
>Dear Friend,
>
>I would like to thank Thomas E.Eichhorst, Paul Callomon
>and Fred Vervaet which answered to my old message.
>Obviously I was joking writing :...and in the meantime I don't know
>what to write on the labels of many Olives which I own.
 
You are not alone!!!!
 
>This is the last between the problems I have collecting these
>shells. The real problems come from their intraspecific
>variability. There are two kinds of this variability:
>A) In this first type many color forms of the same species live
>    all together in the same place. For instance if you are
>    looking for Oliva bulbosa Roding, 1798 to Zanzibar Is.,
>    Tanzania (East Africa) you surely will find all its color form
>    as bicingulata, lacertina, fabagina, undata, aurata, immaculata
>    tuberosa and inflata. But you surely will find also many
>    intermediate color forms. The same is for Oliva oliva Linnaeus,
>    1758 or Oliva fumosa Marrat, 1871 and many other species.
>    In this case only the colors, the pattern and the size change.
 
I guess starting out in fossils first and then branching into recent
Olividae, color has not been something that I have had to deal with much
with the fossils or think about except in very rare cases where patterns
were preserved (not color).  I believe that color has a lot to do with what
metals/organics are available in the sediment.  I remember in Papua New
Guinea many years ago how dark the color patterns were on the Olives due to
the fact that they were crawling around in black volcanic sand versus what
you see in the same species when it is in coral sand.  I have also noticed
this for specimens that I have bought from other volcanic islands in the
Indo-Pacific.  For Oliva sayana Ravenel,1834 in the Gulf of Mexico, most
specimens are rather light in color, since they inhabit light-colored
sands, however in north Florida west of Fort Walton Beach, there is an area
of dark grayish sand (probably with a high organic content) and there I
have found really dark-colored specimens even with a darken protoconch.
 
When I am looking at taxonomy of the Olividae I tend to totally ignore the
color since it is so variable depending on the local ecosystem.  In fact
the color is sometimes very distracting, never the less very attractive.
Having mainly work on fossil Olividae, I have totally relied on the
physical features of the shells (since the animals are not available), e.g.:
 
the number and shape of the nuclear whorls,
the nature of the first teleoconch whorl,
the width and depth of the suture,
the nature of the intrasutural callus,
the overall nature of the slope of the spire (concave or convex).
 
Other factors that may be variable in a species are:
 
height of spire,
number and strength of lirae and plications,
degree of convexity or concavity of spire,
extent of coverage of intrasutural callus.
 
Even using these criteria, sometimes it is difficult to separate out
populations.  Note my emphasis on populations, you need to look at the
variation within a potential species and looking at populations in
different areas (recent) or different stratigraphic layers (fossils) to
help you to document the variation.  I have seen fossil species that vary
from being oval in shape with a very high spire to being squat and
cylindrical - all in the same species because my diagnostic criteria
mentioned above did not vary.  The shape and number of whorls in the
protoconch is probably the biggest discriminator in species of Oliva that
look alike.  It also provides a way of tracing where current species
evolved from during the Tertiary.
 
In recent years Bernard Tursch, Dietmar Greifeneder, Ralph Duchamps and
others have developed a quantitative method for discriminating species of
recent Oliva (mainly in the journal Apex) based on physical measurements.
Their work is the first Oliva species discrimination based on quantitative
measurements of different features of the teleoconch whorls and the
protoconch whorls.  In stead of using "actual measurements", since you can
have variations within a species (i.e., some taller, shorter, thinner or
more obese), they use ratios of the parameters.  Not all parameters/ratios
can adequately discriminate, but they usually find at least two that they
can plot on a x-axis/y-axis plot and delineate species.  They have been
very successful over the last few years in working through the incredible
number of species, subspecies and forms that have been named over and over
through the years, by doing the measurements on the "types" and the
material in their own collections to get larger populations.  Not only have
they shown in many areas that many species names are invalid, they have
actually recently named a new species in the Indo-Pacific that has been
overlooked in the past, since people tend to look at color variations and
general shell characteristics, in some cases, when identifying Olives and
not structural measurements.
 
I am using their technique on the fossil Olividae in a paper that I am
working on now and any future studies.  I will also extend it to Olivella
which will all be done under a microscope or with microphotography.
 
Maurizio, you mentioned above a couple of species where color is very
variable, and people are just naming "subspecies" or "forms" based on the
colors.  When photographing recent species, to bring out the structural
detail, I will often coat them with ammonium chloride (to make them white)
and one tends to see more of the detail of the structure and not get
distracted by the color.  This is similar to what Axel Olsson did in his
1956 Olivella paper and the technique used by the Vokes in their studies.
It is very unfortunate the Oliva oliva is the type species for Oliva, since
it is one of the more variable Olive species in the world.  On the other
hand, it points out the problems with variability within in a species of
Oliva depending on the local ecosystems.
 
>B) In this second type each color form of one species live in
>    different locality. And each color form (or perhaps subspecies ?)
>    makes an homogeneous population where each specimen is
>    very similar to the others. This is the case of Oliva reticularis
>    Lamarck, 1811 (East Central America) and Oliva spicata
>    Roding, 1798 (Western Central America). For instance the
>    specimens of spicata which live on Coronado Is. ( Middle of
>    Gulf of California) are very different from the ones which live
>    on Balandra Bay (South of Gulf of C.) and both are very, very
>    different from the spicata which occours in Panama's waters.
>    I think also Oliva miniacea Roding, 1798 , the Red-mouth
>    Olive, shows this kind of variability. Indeed there are red-mouth
>    where the red is...grey, cream, light blue and also...white !!
>    In these Olives all seems to change : the pattern, the color,
>    the size and also the shape (or outline).
>It's in this last kind of variability that I feel the necessity to identify
>clearly each population waiting for someone finds if they are the
>same species, subspecies or simply color forms.
 
Yes, keep your populations separated and if you do not stay with the
subspecies or form names, you can always call them Oliva spicata population
#1?  This is what I do with my fossils.  Oliva reticularis (in the
Caribbean and down the east coast of South America) and Oliva spicata (in
the Panamic Province) are two examples of highly variable species which are
also probably related prior to closure of the seaway across southern
Central America during Tertiary times.  In the case of Oliva reticularis,
there has been an incredible number of species and subspecies named for
isolated populations (e.g., islands in the Antilles), in which some
variability of shape (spire height versus general shape), color or changes
in pattern has cause new species to be named, or if it is from deep water.
 
I have always thought that there were three basic species of Oliva in the
Caribbean: Oliva reticularis Lamarck, 1811, Oliva scripta Lamarck, 1811
(aka caribaeensis Dall & Simpson, 1901) and Oliva fulgurator (Roding,
1798).  The recent article by Tursch, Greifeneder and Huart (Apex, v 13, no
1-2, April 1998) has shown, using their quantitative methods that there are
only 2 species of Oliva in the Caribbean: Oliva scripta Lamarck, 1811 and
the Oliva "fulgurator-reticularis" complex which is now designated as Oliva
fulgurator (Roding, 1798) since it is an earlier name.  Too bad, I was
hoping that Oliva fulgurator would be a separate species.  Now the Oliva
"fulgurator-reticularis" is highly variable with different "forms"
occurring in every niche and cranny of the Caribbean.  But, there is
another species, Oliva scripta, that usually occurs side by side with the
Oliva "fulgurator-reticularis", that is one of the most constantly shaped
and colored species of Oliva that I have ever seen.  So here you have one
species that its shape and color is all over the map, and another that is
as invariable as a species can be.  Anybody have any ideas why the two
species would evolve with divergent growth patterns when they occur
basically side-by-side in many cases in the same ecosystem?
 
By the way, the article by Tursch et al also describes the equally complex
Oliva "spicata" complex.
 
Maurizio, I have many of Petuch's and Petuch and Sargent names in my
collection, which I have put "reticularis" in front of his/their species
name.  Even with the work by Tursch et al, I am not going to go back and
change all the names to Oliva fulgurator.  At present I want to keep the
"old" names since they do represent local variations in a species complex.
I knew in my own heart that Petuch and Sargent were way over naming the
species in the Caribbean, that is why I have kept the "reticularis" in
front of those names in my labels and my database.  I would do the same for
your Oliva "spicata" complex.
 
Well, I have rambled on too much as it is!!
 
Paul
>
>Warmest regards to all, Maurizio.
>======================
>       Maurizio A. Perini
>       Via Pedrazza, 9
>       I - 36010 Zane (VI)
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