World Congress of Malacology Antwerp ... - Unitas Malacologica

margaritifera, M. auricularia, Unio crassus, U. mancus), but a poor understanding of the systematics
and taxonomy of the group jeoperdizes the efficiency of conservation efforts.
Following the recognition of the endemic character of the Portuguese Unio crassus sensu Haas, based
on molecular phylogenetic analyses, we redescribed this species that was first designated as Unio
tumidiformis Castro, 1885. We revised the collections in the zoologic museums of Lisbon, Coimbra
and Porto (Portugal), Madrid (Spain) and Paris (France) and made extensive samplings throughout
the Iberian Peninsula. We analysed its distribution, morphology, anatomy and life cycle. U.
tumidiformis is restricted to the southern Atlantic basins of the Iberian Peninsula with an enfasis on
the Guadiana basin. This small species, rarely over 5cm in length, is very uncommon with many
populations represented by only a few individuals. It shares some morphologic characters with
central and northern european U. crassus, its genetic sister group, clearly distinct from all other
european Unio. It lives in small streams burried in fine sediment near the banks. Females with
glochidia can be found between March and July. Glochidia are 200µm in length and released as a
loose conglutinate. Five fish species of the genus Squalius were determined to be good hosts for the
species. Metamorphosis takes place in 10 days at a average temperature of 22ºC. Neither Habitat nor
fish hosts explain its restricted distribution, which must have origin in its long evolutionary history as
evidenced by molecular phylogentic analyses.
U. tumidiformis will retain the legal conservation status of U. crassus in the E.U. Habitats Directive,
but its very restricted distribution, rarity and the sensitivity of its habitat to more and more frequent
and extreme drought events should draw special attention to it.
Sperm precedence and lifetime fecundity of Deroceras panormitanum
Reise, Heike 1 ; Sauer, Josefine 1 ; Matthieu, Christiane 1 ; Matton, Sabrina 1 ;
Hutchinson, John M. C. 1,2
1. State Museum of Natural History Görlitz, PF 300 154, 02806 Görlitz, Germany,
Email: Heike.Reise@smng.smwk.sachsen.de; majmch@googlemail.com
2. Max Planck Institute for Human Development, Berlin, Germany
We are using the terrestrial slug Deroceras panormitanum as a model species to investigate whether
sexual conflict has driven the radiation of this speciose genus. In this context it is of relevance to
learn to what extent later matings reduce the paternity of earlier partners. D. panormitanum is a
simultaneous hermaphrodite, and mating involves mutual, external exchange of single packages of
ejaculate from penis to penis. It will mate repeatedly, even a few days after an earlier mating. We
used laboratory stocks of three colour morphs with a simple Mendelian inheritance pattern to
investigate paternity. Virgin slugs were mated twice to different virgin partners separated by an
interval of 5-7 days. We also compared lifetime fecundity of the double-mated slugs and their singlemated
partners. Slugs significantly more often produced no offspring if single mated rather than
double mated, suggesting that matings often fail (possibly because of unsuccessful sperm transfer,
defective sperm, or genetic incompatibility). Even excluding these non-fertile individuals, the
lifetime fecundity of single-mated slugs was significantly lower, suggesting that slugs might become
sperm depleted. Surprisingly, there was no indication that later mating reduced paternity of the first
partner. 44% of double mated slugs with offspring produced offspring of mixed paternity, often even
within single clutches. Mixed paternity was always strongly biased towards one father, but there was
no consistent sperm precedence according to mating order or colour morph. There were several cases
of self-fertilisation, but nearly all involved very few offspring. Slugs laid a succession of clutches
over several weeks, with clutch size and hatching proportion tending to decrease. Maximum
fecundity was 354 hatchlings. Fertile eggs were laid up to 82 days after sperm receipt. Ongoing
experiments test whether the increased fecundity of double-mated slugs depends on whether the
second mating is with the same partner or another.
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