Small specimens of "C. fluminalis" are almost spherical, while those of "C. fluminea" are decidedly flattened. All these differences except the rib number are a consequence of "C. fluminalis" having a markedly more swollen, pointed and protruding umbo. ^ Weitere, M. et al. (2009) Linking environmental warming to the fitness of the invasive clam Corbicula fluminea, Global Change Biology, Volume 15 Issue 12, Pages 2838 - 2851