World Congress of Malacology Antwerp ... - Unitas Malacologica

Molecular systematics of North American Ferrissia (Pulmonata: Ancylidae)
Walther, Andrea
Museum of Zoology, University of Michigan, 1109 Geddes Avenue, Ann Arbor, Michigan, 48109-
1079, USA,
Email: awalther@umich.edu
Members of the ancylid gastropod genus Ferrissia (Walker, 1903) are characterized by fine radial
striae on their shell apices. They have a near-cosmopolitan distribution in freshwater ecosystems but
have received relatively little systematic attention in recent decades. In North America, the last major
study was that of Paul Basch (1963), who recognized 5 Ferrissia species but stated I have found no
way to separate species unequivocally, and believe that they may all represent different directions of
clinal variations within one large super-species. I aim to revisit the systematics of North American
Ferrissia nominal taxa using molecular phylogenies to resolve taxonomic ambiguities. I obtained
samples of the constituent nominal species from throughout their ranges in North America and
utilized nuclear and mitochondrial markers to generate representative gene trees. My findings reveal
that two primary lineages of Ferrissia occur in North America and that they are not sister taxa, but
form a paraphyletic clade also containing Ancylus and Rhodacmea species. One Ferrissia lineage
appears to be restricted to North America and is comprised exclusively of individuals from two
nominal species: the lotic F. rivularis and the lentic F. parallelus. These species are taxonomically
polyphyletic, and the within-clade topology exhibits a pronounced geographic east/west structuring
with evidence of limited secondary movement from east to west. The other primary North American
lineage comprises F. fragilis, a minute pond-specialist capable of aestivating under drought
conditions by producing a septum. F. fragilis has Old World sister lineages, but it has recently
become globally invasive, establishing cryptic alien populations in tropical Asia and throughout
Europe. It was first documented in Europe 60 years ago and has since been sequentially recorded
across much of the continent as F. wautieri or F. clessiniana. It may well be establishing cryptic
invasive populations in temperate and tropical freshwater pond ecosystems worldwide.
Preliminary studies on the occurrence of the Asiatic clam Corbicula fluminea (O.F. Müller,
1774) (Bivalvia: Corbiculidae) in River Odra (Poland)
Wawrzyniak-Wydrowska, Brygida
University of Szczecin, Department of Palaeoceanology, Waska 13, 71-415 Szczecin, Poland,
Email: wydra@univ.szczecin.pl
Corbicula fluminea (O.F. Müller, 1774) is a south-eastern Asiatic species which has been expanding
to other continents since the early 20th century; it is now known from European rivers. The first
Polish record of C. fluminea dates back to October 2003 when the bivalve was found in a power
station cooling water canal in the downstream reaches of River Odra (NW Poland). It is not known
how far the species has been dispersing in the river since and what dispersal means and pathways
have been used. To elucidate the present range of C. fluminea in River Odra, as of spring 2005,
regular surveys were performed along the entire course of the Odra (from its origins in the Czech
Republic to the discharge to the Pomeranian Bay, Baltic Sea). The surveys were repeated in summer
and autumn 2005 and were continued throughout 2006. In 2005, no live C. fluminea were found, nor
were empty shells present in the samples. In May 2006, however, live specimens were retrieved from
samples collected in the middle and upper reaches of the river; in addition, empty shells were found
in the river bank deposits, particularly at sites showing traces of former elevated water levels.
Subsequently, particularly in October 2006, the bivalve was observed to have clearly expanded its
range as the number of live individuals distinctly increased; an elevated amount of empty shells was
recorded as well. The bivalves occurred at sandy and sandy-muddy sites. The periostracum of most
individuals from sandy bottoms was yellow-olive in colour, brown coloration being typical of shells
from muddy sites. The mean shell dimensions of both live individuals and empty shells indicate the
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