World Congress of Malacology Antwerp ... - Unitas Malacologica

century conchologists. In the past twenty five years of land snail surveys in Thailand many
Amphidromus specimens have been collected and a good deal of information on their distribution and
life history has been accumulated. In addition to its striking appearance and interest to shell collectors
Amphidromus proves to be an informative and fascinating subject for studies in systematics and
evolutionary biology. We have harnessed the tools of allozyme analysis and constructed phylogenies
based on mtDNA as well as comparative morphology to gain an understanding of population
dynamics, species limits, relationships and distribution. The example of Amphidromus in exhibiting
stable whole-body enantiomorphy is unique and the subject of a recent study. Our studies are timely
in trying to gain an insight into the evolutionary history of the group because the natural habitat
islands occupied by Amphidromus have been greatly depleted by human exploitation much having
been lost during the period of our surveys, and populations are increasingly isolated in fragments of
their previous range.
Achatinellid land snails of the Pacific islands: phylogenetics, phylogeography and evolution
Parker, Meaghan E.
Department of Zoology, University of Hawaii, Honolulu, Hawaii 96822, USA,
Email: meaghan@hawaii.edu
The Pacific island orthurethran land snail family Achatinellidae includes five subfamilies: the
endemic Hawaiian subfamilies Achatinellinae and Auriculellinae, and three Pacific-wide subfamilies,
Pacificellinae, Tornatellininae and Tornatellidinae. The Achatinellinae, which include the
conspicuous and endangered Oahu tree snails (genus Achatinella), exhibit great variability in shell
color and banding pattern and have as a result attracted much scientific interest. The other four
subfamilies include smaller, less colorful snails and have consequently attracted less attention. This
study addresses the phylogenetic relationships among species in the four non-achatinelline
subfamilies. Partial mitochondrial DNA cytochrome c oxidase subunit I (COI) gene sequences have
been obtained from 250 individuals from 26 sites on four of the main Hawaiian Islands and from four
sites in the Ogasawara Islands of Japan. Using a pupilloid outgroup (also Orthurethra), these
preliminary results indicate that: 1) CO1 is appropriate for resolving species, genera and subfamily
relationships (although some of the deeper nodes are not well supported); 2) the four nonachatinelline
subfamilies are supported as monophyletic groups 3) one species appears to have
colonized Ogasawara from Hawaii, either naturally or through human introduction; and 4) many sites
in Hawaii harbor more than one species. These data on the four non-achatinelline subfamilies
complement published research on the phylogenetic relationships in the subfamily Achatinellinae,
and with more comprehensive data to be collected in the future will permit a broad understanding of
the evolutionary relationships and biogoegraphy of the entire family.
Sexual dimorphism in the shells of the South-Western Atlantic gastropod Olivella plata
(Ihering, 1908) (Mollusca: Olividae)
Pastorino, Guido
Museo Argentino de Ciencias Naturales, Av. Angel Gallardo 470 3° piso lab 80, C1405DJR Buenos
Aires, Argentina,
Email: gpastorino@macn.gov.ar
Most known cases of sexual dimorphism in molluscs are based on size differences. A remarkable
case of structural sexual dimorphism recorded during a revision of the genus Olivella from Argentine
waters is presented. Over 200 specimens of Olivella plata (Ihering, 1908) were collected at Villarino
(42°24’S-64°15’W) in Golfo San José and Punta Pardelas (42°37’S-64°15’W) in Golfo Nuevo, both
localities from Chubut province, northern Patagonia. Each live specimen collected was sexed based
on the presence of penis and the pedal gland. Female shells are easily recognised as they show an
anterior wide vertical groove, adjacent to the parietal callus and the pillar structure. The groove is not
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