World Congress of Malacology Antwerp ... - Unitas Malacologica

populations. Copulation duration differed among populations studied but a specific pattern related to
habitat characteristics was not evident.
Spermathecal morphology did not differ significantly among populations coming from the mainland
of Greece. The number of the spermathecal tubules ranged in mainland populations from 3 to 21. In
populations from Crete the number of the spermathecal tubules ranged from 1 to 11 and differed
significantly from the corresponding number of the mainland populations.
Exploring biodiversity in caves and limestone: an open window on Polynesia's lost paradise
Gargominy, Olivier; Fontaine, Benoît
Muséum national d'Histoire naturelle, Département Systématique et Evolution, USM 602 -
Taxonomie & Collections, CP 051, 55 rue Buffon, 75005 Paris, France,
Email: gargo@mnhn.fr; fontaine@mnhn.fr
Considering the few early malacologists and the rapid destruction of natural habitats on small oceanic
islands, the molluscan fauna of most Pacific islands is poorly known. But what remains to be
discovered? An inventory was carried out by the French Polynesia government and Muséum national
d’Histoire naturelle (Paris) in Austral Islands, Society Islands and Makatea (Tuamotu Islands) during
the years 2002-2004. While there are still some tiny patches of natural forest in areas such as
mountain summits or deep gulleys, the main source for new species was deposits under limestone
cliffs or in caves. Although these deposits have not been dated yet, it seems reasonable to think that
they are recent - no more than few dozens or hundreds years old, as they are the top layers with
present shells. In this context, and for the family Endodontidae only, Rurutu (32.3 sq. km.) has
revealed a total of 21 species while only 7 were known from the 1934 Mangareva Expedition All
these new species are subfossils and were not found alive despite specific research, i.e. were extinct
at the time of discovering. On Makatea (24 sq. km.), a first estimate has led to more than 20
endodontid species of which only 5 were previously known.
Conversely, collecting on the exclusively volcanic Society Islands has yielded no Endodontidae,
either subfossils or alive, except on the summit of Tahiti’s Mont Aorai (2000 m). Endemic radiations
such as Nesodiscus are now thought to be extinct. Deposits containing molluscs are much rarer than
in limestone areas. So, whether limestone was a factor influencing radiation or simply represents an
artefact of the past diversity may remain an unsolved question.
Microgastropod population changes from the Late Cretaceous to recent in the Gulf Coastal
Plain of the USA
Garvie, Christopher, L.
Texas Natural Science Center, University of Texas, Austin, Texas, 78705, USA,
Email: cgarvie@austin.rr.com
A large collection of over 150,000 mollusk specimens from the Cretaceous through Recent of the
Gulf Coast is analysed to determine changes in the microgastropod populations. Four major
assemblage groups are recognized, an early Cretaceous assemblage dominated by Turritella, Nerinea
and Nerita, a changeover from a Trochoidea to a Philinoidea dominated assemblage in the late
Cretaceous, and its increasing dominance until the end of the Oligocene, and a more evenly
distributed late Neogene assemblage. In addition it is found that microgastropod populations show
much more sensitivity to environmental changes than do populations of larger gastropods.
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