Bivalves from the latest Jurassic-earliest Cretaceous hydrocarbon seep carbonates from central Spitsbergen, Svalbard Author Hryniewicz, Krzysztof krzysztof.hryniewicz@nhm.uio.no Author Little, Crispin T. S. earctsl@leeds.ac.uk Author Nakrem, Hans Arne krzysztof.hryniewicz@nhm.uio.no text Zootaxa 2014 2014-09-02 3859 1 1 66 journal article 4900 10.11646/zootaxa.3859.1.1 d866af6f-cbcd-47f4-a4f3-1499c1789ae3 1175-5326 4930112 24FCAAE1-AB7C-4FAD-8698-D0C9F12400EC Family Nucinellidae Vokes, 1956 Genus Nucinella Wood, 1851 Type species. Pleurodon ovalis Wood, 1840 Remarks. Nucinella has sometimes been placed in the family Manzanellidae Chronic, 1952 (e.g. Amano et al. 2007; Kiel et al. 2008a ). However, the Permian genus Manzanella Girty, 1909 , is longer than high, with roughly equidistantly positioned beaks. Furthermore, it is dimyarian, with anterior and posterior adductor muscle scars roughly equal in size ( Chronic 1952 ). This contrasts with the genus Nucinella Wood, 1851 , which is monomyarian and has a very short posterior shell margin (e.g. Allen & Sanders 1969 ). A dimyarian condition was previously postulated for the supposed sister genus Huxleyia Adams, 1860 (e.g. Habe 1958 ; pl. 9, fig. 16; La Perna 2004 , p. 571). However, investigation of Huxleyia habooba Oliver & Taylor, 2012 , and Huxleyia sulcata Adams, 1860 , revealed no sign of a posterior adductor muscle, which supports separation of Nucinella and Huxleyia into a separate family Nucinellidae ( Oliver & Taylor 2012 ) , with Manzanellidae restricted to the genus Manzanella .