[I forwarded the debate on Trophon classification to Dr. Guido Pastorino
<[log in to unmask]>, who received a Conchologists of America Grant
last year to work on Trophon classification. This is his reply, which I post
with his permission.]
After sometime working with the Trophon group I think there are
statements that should be taken very carefully or in a different way. Let
see the reasons that Greg Herbert point out to establish the "unstability"
of the Trophon group
1) Convergence in shell morphology with other muricids
I agree in this point however there are several characters that are rather
exclusive from the Patagonian group of Trophon species. Unfortunately in the
last years several new genera and species are described without accurate
geographic location or with the shell only and this is unacceptable today or
at least unuseful. Some features like the radula are a very interesting tool
when you have the whole stuff between hands.
2) many species come from cold, deep waters
Most of the species are from temperate or cold waters however the type
species of the genus T. geversianus is from very shallow water (intertidal)
T. pelseneeri, Coronium coronatum, C. elegans, C. oblongum and T. acanthodes
are present in Brazil in less than 100 meters from the lots I have seen.
T. albolabratus, T. amettei, T. brevispira, T. distantelamellatus, T.
leptocharteres, T. longstaffi, T. minutus, T. pallidus T. nucelliformis and
the whole genus Xymenopsis are living in less than 50 m sometimes intertidal
too.
3) There is no fossil record
The Trophon group is very well represented in Miocene and earlier in
Tertiary strata of Patagonia.To mention some who worked on fossil Trophon in
the area, Darwin (in London), Ortmann (in Purdue, IN) and Pilsbry (in the
ANSP) (none from private collections) described several new species some
time ago, and recently Brunet (1997 Tulane Studies in Geology and
Paleontology 30(2):61-98) described more than 17 new fossil species
belonging to Trophoninae from only one locality in Patagonia!!! I went down
there several times and I know that this is only the tip of the iceberg.
4) Most of museum collections of muricids are composed of dry lots
donated by private individuals.
Together the collection of the USNM, the Museum of Buenos Aires and La
Plata, have more than 1000 specimens in 600 lots of (most of them) wet and
dry specimens only of Trophon, all of them collected by several Antarctic
Expeditions from both countries. Again everything is little when you deal
with this group. All I can say is that I have a complete series of the South
American and Antarctic species of Trophon. I was able to dissected the
radulae of the 95 % of the species of the area and did anatomy of
approximately 80 % of them. The picture of the Trophon is starting to be
clear, at least I know now, that from the original 100 names, less than 40
are valid species for the area.
Two groups are very clearly defined in the South American and Antarctic
area: one from Patagonia with a very remarkable similarities in radula and
anatomical features like salivary glands, female and male reproductive
systems, protoconch morphology, etc and the Antarctic one with a different
set of characters. This allows me to consider that the evolution of the
group since the tertiary was isolated in Patagonia. The Antarctic group on
the contrary is very different from the Patagonian one and among them.
Recently I started with some histology of some systems (genital), I think
this kind of studies can help. The question that remains without a
definitive answer is about the relationships with the other representatives
of the world like Boreotrophon. And with the other Muricidae subfamilies.
I'm working on it. However, what I consider the Trophoninae as a very
stable group is living since the Tertiary in Patagonia and has at least 18
valid species.
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Gary Rosenberg, Ph.D. [log in to unmask]
Malacology & Invertebrate Paleontology gopher://erato.acnatsci.org
Academy of Natural Sciences http://www.acnatsci.org
1900 Benjamin Franklin Parkway Phone 215-299-1033
Philadelphia, PA 19103-1195 USA Fax 215-299-1170
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