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Viviparus contectus (Millet, 1813)
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Species name:
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Viviparus contectus (Millet, 1813)
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Taxon name:
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Cyclostoma contectum Millet, 1813
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Originally described in:
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Millet, P. A. 1813. Mollusques terrestres et fluviatiles, observés dans le Département de Maine et Loire. - pp. j.xj [= 1-11], 1-82, 1 tableau. Angers. (Pavie).
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Distribution:
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N and central Europe to Slovakia, N Spain and Portugal, mainland Italy, Balkans to Makedonija and Greece (not Norway, not Finland, in SE Sweden S of 57°N)
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Diagnosis:
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Shell evenly greenish brown or with blurry colour bands, often with hammer pattern, apex strongly pointed, 5.5-6 strongly convex whorls with deep suture, umbilicus narrow but open.
Differs from V. viviparus in its pointed apex.
Animal blackish or greenish, with many yellow dots, tentacles long, in males the right tentacle is shorter, eyes big, circular and black, located on two small tubercles at the base of the tentacles.
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Size:
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25-55 x 20-40 mm, very variable, females are larger than males
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Biology:
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Standing small and large waters with rich vegetation, swamps and temporary water bodies. Tolerates acid water and up to 0.4 % salt. Artificially created new habitats are rarely accepted in Austria. In N Italy up to 4-10 m deep, maximum 15 m. In Switzerland up to 400 m, in Germany 800 m. Feeds grazing on mud, or by filtrating water. Animals dig into the muddy substrate to hibernate.
In N Greece reproduction takes place in spring and autumn, sex ratio is 1:1 (also in E Poland), in Greece and France 12-30 egg capsules are present in the uterus of females (in Poland 5-15, in autumn less), the 2.5-10 mm sized juveniles hatch in the course of the summer, maturity is reached after 3 months for the spring generation and 8 months for the autumn generation, at 17 mm shell height, life span up to 13 years, in Greece around 5 years. Females may retain embryos at water temperatures below 15°C, they migrate from 0.5 m to deper water (1-2 m) in October and hibernate in the mud, to give birth in the next season.
Fertile hybrids with Viviparus ater are possible, but possibly unlikely under natural conditions.
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Threatened:
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Rare in Portugal. Threatened by industrial and agricultural water pollution, closing of small water bodies due to agricultural land use, drainage, sinking of ground water levels. There were unsuccessful attempts to establish populations in the lakes of Zurich and Geneva. Clearly declining in N England and around London (1999). Has seriously declined in Austria due to habitat destructions, this includes its occurrence in Donauauen National Park where most freshwater molluscs have seriously declined before 2009 due to mismanagement.
Endangered in Switzerland and large parts of W Germany (Baden-Württemberg, Hessen, Nordrhein-Westfalen), vulnerable in Germany and Austria.
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Family:
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Viviparidae
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Higher group:
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Gastropoda
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Comments:
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The names V. viviparus and V. contectus were not consistently used until 1959, previous reports of V. viviparus partly included V. contectus (and sources which worked with information published before 1959).
In Moldova in Răut and Nistru/Dniestr river basins, rarer than V. viviparus (V. Coada, unpublished, 2011).
References: Germain 1931: 600 (V. fasciata), Nobre 1941: 218, Falkner 1990: 118, Vogt et al. 1994: 39, Bodon et al. 1995: 21, Eleutheriadis & Lazaridou-Dimitriadou 1995 (2 papers, life cycle Greece), Turner et al. 1998: 72, Kerney 1999: 26, Falkner et al. 2001: 14, Glöer 2002: 63, Glöer & Meier-Brook 2003: 30, Cioboiu 2006 (only in some parts of Romania), Reischütz 2009, Jakubik 2009 (life cycle Poland), Welter-Schultes 2012: 32 (range map).
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