World Congress of Malacology Antwerp ... - Unitas Malacologica

keys for micromollusc samples: The distinction of immature stages of larger species and adults of
smaller species is critical in most groups except for those showing the sign of maturity in the shell
(determinate growth).
Anatomy of Eulepetopsis vitrea McLean, 1990 (Patellogastropoda: Neolepetopsidae)
Sasaki, Takenori 1 ; Warén, Anders 2
1. The University Museum, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033,
Japan,
Email: sasaki@um.u-tokyo.ac.jp
2. Swedish Museum of Natural History, Box 50007, SE-10405 Stockholm, Sweden
Neolepetopsidae is one of families newly discovered from hydrothermal vents in the late 20th
century. It was originally classified as an independent suborder (Lepetopsina) in Patellogastropoda,
but such treatment was questioned by subsequent authors. To obtain more detailed evidence for
phylogenetic estimation, we investigated the anatomy of Eulepetopsis vitrea, using gross dissection,
serial sectioning and scanning electron microscopy. As a result, the animal of E. vitrea was revealed
to possess the following features: short-type pallial margin tentacles, mouth surrounded by oral
lappet, pedal wall lacking pallial ridges, ctenidium and osphradia entirely missing, unique
configuration of alimentary tract, reduced salivary glands, small angle of oesophageal torsion, paired
openings into digestive glands, acmaeoidean-type buccal musculature, dorsal protractor muscle of
odontophore thin and widely covering buccal mass, two pairs of odontohporal cartilages, ventrally
positioned thin approximator muscle, rectum bypassing ventricle, statocysts attached to outer lateral
side of pleural ganglia, deeply ramified testis but massive ovary. The combination of above
characters suggests the possible relationships with deep-sea Acmaeoidea (e.g. Bathyacmaea,
Pectinodonta or some lepetids). In contrast, the closeness to Patelloidea (Patellidae and Nacellidae) is
clearly rejected by the fact that there is no uniquely shared character among three families. Further
anatomical investigations are necessary for unstudied subtidal and deep-sea groups (e.g. Acmaea,
Serradonta, many lepetids) to understand the phylogeny of whole patellogastropods.
Comparative analysis of land snail radiations on Crete
Sauer, Jan; Hausdorf, Bernhard
Zoological Museum, University of Hamburg, Martin-Luther-King-Platz 3, D-20146 Hamburg,
Germany, Email: ja_sa@web.de; hausdorf@zoologie.uni-hamburg.de
To investigate the causes for the land snail radiations on Crete we studied the systematics and
phylogeny of the radiation of the genus Xerocrassa on Crete using morphological characters,
mitochondrial (cox1, 16S rDNA) and nuclear (ITS2) DNA sequences and AFLP markers. Twelve
Xerocrassa species occur on Crete, six of which have not been described so far. Distribution maps of
these species were based on almost 3000 records. With these data and corresponding data on other
Cretan land snail radiations, especially of the genera Mastus and Albinaria, we tested the hypothesis
that these radiations were the result of a fragmentation of Crete into several paleoislands during the
late Miocene and Pliocene. Contrary to the predictions of this hypothesis, Monte Carlo simulations
showed that the distribution areas of the Cretan endemics are not significantly clustered and the
phylogenies of the radiations do not reflect a common pattern. These results indicate that the land
snail radiations on Crete were not caused by a common sequence of vicariance events. Probably,
stochastic events like chance colonization of isolated habitats were more important. Although most
sister clades of Cretan Xerocrassa species are allopatric and show strong range size asymmetry as
predicted by the peripatric speciation model, a test for peripatric speciation based on a Monte Carlo
simulation of range size asymmetry was non-significant. This indicates that different speciation
modes might have been involved in the radiation of Cretan Xerocrassa species. Hardly any habitat
differences between Cretan Xerocrassa species can be identified. Thus, the radiation is apparently
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