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Sphaerium rivicola (Lamarck, 1818)
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Species name:
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Sphaerium rivicola (Lamarck, 1818)
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Taxon name:
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Cyclas rivicola Lamarck, 1818
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Originally described in:
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Lamarck, J. P. B. A de Monet de 1818. Histoire naturelle des animaux sans vertèbres, présentant les caractères généraux et particuliers de ces animaux, leur distribution, leurs classes, leurs familles, leurs genres, et la citation des principales espèces qui s'y rapportent; précédée d'une introduction offrant la détermination des caractères essentiels de l'animal, sa distinction du végétal et des autres corps naturels, enfin, l'exposition des principes fondamentaux de la zoologie. Tome cinquième. - pp. [1-3], 1-612. Paris. (Deterville, Verdiere).
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Distribution:
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Central and E Europe (not Alps), England
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Diagnosis:
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Shell solid and finely ribbed, olive greenish or brownish, with some pale yellowish zones, sometimes with slightly darker transversal streaks, weakly shiny, almost opaque. Juveniles slightly more elongated and evenly yellow.
Animal yellowish grey or brownish, gills brownish or reddish, siphons whitish and almost equally short. External gills 6 x 1.5 mm.
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Size:
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10-16 x 15-25 x 17-20 (height) mm
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Biology:
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Restricted to large rivers and canals, prefers silent zones and well-oxygenated hard-water. In Britain nearly always associated with Viviparus viviparus, in relatively deep water.
Juveniles or eggs can sometimes be seen at the exterior gills. After hatch the juveniles have a diameter of 4 mm, they are relatively flat with a large foot, the mother makes them leave quickly.
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Threatened:
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Threatened by pollution and habitat change, some populations in England were lost.
Critically endangered in Germany (extinct in Thüringen).
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Family:
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Sphaeriidae
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Higher group:
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Bivalvia
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Comments:
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References: Moquin-Tandon 1855: 590, Locard 1882: 254 (N and central France, rare in Midi, not S France), Jungbluth et al. 1989: 220, Falkner 1990: 268, Vogt et al. 1994: 239, Kerney 1999: 215, Korniushin 2001: 80, Jungbluth & Knorre 2009: 10, Welter-Schultes 2012: 25 (range map).
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