76. Sphaerium rivicola (Lamarck, 1818)

Findings in Serbia.

Sphaerium rivicola: Arambašić (1994); Tomović et al. (2010 b, 2014); Paunović et al. (2005, 2007 b, 2008); Martinović-Vitanović et al. (2007, 2013); Lucić et al. (2015).

Common name. River orb mussel, nut orb mussel.

Morphology. Small bivalve. Shell is rounded oval in outline shape and typically reaches 18–22 mm in length, 15–17 mm in height, and 10–13 mm in depth (more details in Welter-Schultes, 2012, page 25, figure in the middle of the page).

Distribution and ecology. Palearctic species common in the lowland regions of Central and Eastern Europe (Zhadin 1965). It prefers fine substrate (silt, mud, sand) in larger slow–flowing rivers and canals, rarely it could be found in standing waters. In Serbia, it mostly inhabits large Pannonian/lowlands rivers (the Danube, Tisza and Sava Rivers).

Other remarks. One of the largest species of Sphaerium occurring in Serbia. There are 10 nominal species known as synonyms (Graf & Cummings 2021). On the IUCN Red List of threatened species it has been assessed as LC, yet with decreasing population trend, for Europe (von Proschwitz & Killeen 2011), and as VU on the global scale (Van Damme 2011 d).