World Congress of Malacology Antwerp ... - Unitas Malacologica

and collected on the gill in suspension-feeding species. In the vascular system a muscular, chambered
heart pumps water through arteries, interstitial spaces, and veins. In contrast, cilia on the surface of
the gill pump water through the mantle cavity. Flow rate appears to depend upon the diameters of the
incurrent and excurrent openings of the mantle cavity, which are controlled by the muscle and
connective tissue fibers in the mantle tissue.
Pleistocene refugia in Patagonia:
Evidence from the freshwater snail genus Chilina (Gastropoda: Chilinidae)
von Oheimb, Parm Viktor 1 ; Riedel, Frank 2 ; Wilke, Thomas 1
1. Department of Animal Ecology and Systematics, Justus Liebig University Giessen, Heinrich-Buff-
Ring 26-32 (IFZ), D-35392 Giessen, Germany,
Email: Parm.von.Oheimb@gmx.de, Tom.Wilke@allzool.bio.uni-giessen.de
2. Department of Earth Sciences, Institute of Geological Sciences, Centre for Ecosystem Dynamics,
Freie Universität Berlin, Malteserstr. 74-100, Haus D, 12249 Berlin,
Email: paleobio@zedat.fu-berlin.de
The evolution of the Patagonian ice fields since the Last Glacial Maximum (LGM) is of great interest
regarding the peopling of the southern cone of South America. It is generally believed that the
homogenous ice sheet made it impossible for humans migrating by boats going further south and
therefore humans migrating through the ice free Pampas were the first reaching the Land of Fire.
There is, however, anecdotic evidence that ice free areas along the western edge of Patagonia existed
that may have permitted an earlier human colonisation.
Here, we use phylogeographical patterns of the freshwater gastropod genus Chilina GRAY, 1828 for
testing the Pleistocene refuge hypothesis in western Patagonia. Chilina is a basommatophoran genus
that is restricted to the southern South America with several described species. The species of this
taxon live in lotic habitats and the occurrence is thus dependant on ice free environments. Therefore,
extant Chilina populations in Patagonia must either have colonised this area after the LGM or have
survived in ice free freshwater areas within Patagonia.
Given this background, we are studying the phylogeography of Chilina spp. from the south-western
parts of South America (Argentina, Chile) using mitochondrial genes (COI, LSU rDNA). Preliminary
phylogenetic analyses show that the individuals studied form three main clades. The first clade
contains most of the individuals collected on the South American mainland. The second clade
consists of individuals collected on offshore islands (Chiloé Island and Wellington Island) and a third
clade is formed by snails from a single mainland locality. We also found relatively high within and
between population diversities that may indicate the existence of ice free freshwater habitats during
the LGM. Multiple immigration events, however, can not be fully excluded as explanation for the
patterns seen in our data. Therefore, we are currently extending our dataset both with additional
populations and additional markers in order to obtain a more precise phylogeographical picture of
this taxon.
Pupilla pratensis (Clessin, 1871) a distinct species in the form group of Pupilla muscorum
(Linnaeus, 1758) (Gastropoda, Pulmonata, Pupillidae)
von Proschwitz, Ted 1 ; Schander, Christoffer 2 ; Jueg, Uwe 3 ; Thorkildsen, Solveig 2
1. Göteborg Natural History Museum, Section of Invertebrate Zoology, P. O. Box 7283, SE-40235
Göteborg, Sweden,
Email: ted.v.proschwitz@gnm.se
2. University of Bergen, Department of Biology, P. O. Box 7800, 5020 Bergen, Norway,
Email: schander@bio.uib.no
3. Schweriner Allee 16, D-19288 Ludwigslust, Germany,
Email: uwejueg@t-online.de
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