World Congress of Malacology Antwerp ... - Unitas Malacologica

dominated by polychaete worm Ditrupa arietina, as well by turrids, usually predators on polychaetes;
abundance of bored bivalve shells indicated the active presence of naticids. The bivalve Ervilia
castanea dominated shallower depths, being gradually replaced by Tellinella donacina and Timoclea
ovata; at greater depths, Tellina balaustina became relatively abundant.
Presentation of this work at the WCM by one the participating undergraduate students (Ana Velosa)
was made possible through a grant from SOGEO/ grupo EDA – Empresa de Electricidade dos
Açores, Lda.
Early ontogeny in buccinid gastropods: inferences from morphology
Vendetti, Jann E.
University of California-Berkeley & Museum of Paleontology, 1101 VLSB, Berkeley, California
94720-4780, USA,
Email: jannv@berkeley.edu
Gastropods in the Family Buccinidae are abundant, diverse neogastropods with interspecific variation
in their larval strategies, or developmental modes. These developmental differences are expressed
during early ontogeny and are reflected in the morphology of larval shells and protoconchs.
According to “shell apex theory”, typical non-planktonic buccinid species (so called “directdevelopers”)
should exhibit a bulbous protoconch and paucispiral larval shell, with little
ornamentation. In contrast, species with planktonic larvae are expected to show morphological signs
of their free-swimming life, in the form of a high-conical shell apex, and a multispiral larval shell
with a sinusigeral ridge. These characteristics plus protoconch size and shape dimensions comprise
the suite of criteria used to distinguish planktonic versus non-planktonic developers in extant and
fossil buccinid taxa. To date, however, there has been no direct study of the suitability of this method
to buccinid gastropods. This study reports on tests of developmental mode criteria using (1) larval
shells of Kelletia kelletii, a buccinid gastropod with planktonic larvae and (2) protoconchs of species
within the genus Bruclarkia, an extinct buccinid gastropod endemic to the Eastern Pacific during the
Eocene, Oligocene, and Miocene. Methods described include larval rearing, fossil collection,
protoconch molding and casting, and scanning electron microscope (SEM) imaging with ImageJ
analysis. Larval shell and protoconch characters are evaluated and the suitability of inferences of
developmental mode from morphology is discussed. The application of this method and its value are
couched in phylogenetic and paleontological context.
Mating behaviour across the contact zone in pairs of sibling slug species
Visser, Stefanie 1 ; Reise, Heike 1 ; Hutchinson, John M. C. 1,2
1. State Museum of Natural History Görlitz, PF 300 154, 02806 Görlitz, Germany,
Email: Stefanie.Visser@smng.smwk.sachsen.de; Heike.Reise@smng.smwk.sachsen.de;
majmch@googlemail.com
2. Max Planck Institute for Human Development, Berlin, Germany
Deroceras is the most speciose genus of terrestrial slugs. Although varying little externally, they
show a spectacular interspecific diversity of penis morphs and mating behaviours. We hypothesise
that the evolution of these traits has been driven by sexual conflict between the mating partners over
the donation and utilisation of sperm, resulting in rapid divergence of geographically isolated forms,
and thus in incompatibility on secondary contact. We studied the mating behaviour of three sibling
Deroceras species (D. fatrense, D. praecox and D. rodnae) in their zones of contact. Our aim was to
test if differences in mating behaviour are accentuated within the very narrow zone in which apparent
morphological hybrids were found; that would suggest reproductive character displacement to avoid
hybridisation after secondary contact. Alternatively, introgression may have resulted in more similar
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