<div>Abstract </div><div>Introduction</div><div>THE SUPERFAMILY MACTROIDEA. </div><div>MORPHOLOGY OF THE GROUP</div><div>SOCIOECOLOGICAL RELEVANCE OF THE GROUP</div><div>THE BIOGEOGRAPHICAL PROVINCES. </div><div><br></div><div>Material and Methods </div><div><br></div><div>Systematic Results </div><div>Family Mactridae Lamarck, 1809</div><div>Subfamily Mactrinae Lamarck, 1809 </div><div>GENUS HARVELLA GRAY, 1853 </div><div>Harvella elegans (G.B. Sowerby I, 1825) </div><div>GENUS MACTRELLONA MARKS, 1951. </div><div>Mactrellona alata (Spengler, 1802) </div><div>Mactrellona clisia (Dall, 1915) </div><div>Mactrellona exoleta (Gray, 1837) </div><div>Mactrellona subalata (Mörch, 1861) </div><div>GENUS MACTROMERIS CONRAD, 1868 </div><div>Mactromeris catiliformis (Conrad, 1867) </div><div>Mactromeris hemphillii (Dall, 1894a) </div><div>Mactromeris polynyma (Stimpson, 1860) </div><div>GENUS MACTROTOMA DALL, 1894 </div><div>Mactrotoma (Mactrotoma) fragilis (Gmelin, 1791) </div><div>Mactrotoma (Mactrotoma) nasuta (Gould, 1851) </div><div>Mactrotoma (Micromactra) angusta (Reeve, 1854) </div><div>Mactrotoma (Micromactra) californica (Conrad, 1837) </div>Mactrotoma (Micromactra) janeiroensis (E. A. Smith, 1915) <div>Mactrotoma (Micromactra) surinamensis (Altena, 1968) </div><div>Mactrotoma (Mactroderma) isthmica (Pilsbry & Lowe, 1932) </div><div>Mactrotoma (Mactroderma) velata (Philippi, 1849) </div><div>GENUS MULINIA GRAY, 1837. </div><div>Mulinia bicolor Gray, 1837 </div><div>Mulinia cleryana (d´Orbigny, 1846) </div><div>Mulinia edulis (King, 1832) </div><div>Mulinia exalbida Gray, 1837 </div><div>Mulinia lateralis (Say, 1822) </div><div>Mulinia levicardo (E. A. Smith, 1881) </div><div>Mulinia modesta (Carpenter, 1864) </div><div>Mulinia pallida (Broderip & G.B. Sowerby I, 1829) </div>Mulinia pontchartrainensis Morrison, 1965 <div>GENUS RANGIA DES MOULINS, 1832 (NON FERUSAC, 1837, NON AGASSIZ, 1860) </div><div>Rangia (Rangia) cuneata (Sowerby I, 1832) </div><div>Rangia (Rangianella) flexuosa (Conrad, 1840) </div><div>Rangia (Rangianella) mendica (Gould, 1851) </div><div>GENUS SIMOMACTRA DALL, 1894D </div><div>Simomactra dolabriformis (Conrad, 1867)</div><div>Simomactra falcata (Gould, 1850) </div><div>Simomactra planulata (Conrad, 1837)</div><div>GENUS SPISULA GRAY, 1837 </div><div>Spisula fuegiensis E. A. Smith, 1905</div><div>Spisula (Spisula) guidoi Signorelli and Scarabino, 2010</div><div>Spisula (Spisula) isabelleana d´Orbigny, 1846 </div>Spisula (Spisula) marplatensis Doello Jurado, 1949<div>Spisula (Spisula) petitii d´Orbigny, 1846</div><div>Spisula (Spisula) williamsi (Berry, 1960)</div><div>Spisula (Hemimactra) solidissima (Dillwyn, 1817)</div><div>Spisula (Hemimactra) raveneli (Conrad, 1832)</div><div>GENUS TRINITASIA MAURY, 1928</div><div>Trinitasia iheringi (Dall, 1897)</div><div>GENUS TUMBEZICONCHA PILSBRY & OLSSON, 1935. </div><div>Tunmbeziconcha thracioides (Adams & Reeve, 1850) </div><div>Tumbeziconcha goniocyma (Pilsbry & Lowe, 1932) </div><div><br></div><div>Subfamily Lutrariinae Gray, 1853</div><div>GENUS TRESUS GRAY, 1853 </div><div>Tresus allomyax Coan & Valentich Scott, 2000 </div><div>Tresus capax (Gould, 1850) </div><div>Tresus nuttallii (Conrad, 1837) </div><div><br></div><div>Subfamily Darininae Signorelli in Carter et al., 2011 </div><div>GENUS DARINA GRAY, 1853. </div><div>Darina solenoides (King, 1832) </div><div>Darina rustica Huber, 2010 </div><div><br></div><div>Family Anatinellidae Deshayes in Gray, 1853</div><div>Subfamily Kymatoxinae Stenzel and Krause, 1957</div><div><br></div><div>GENUS ANATINA SCHUMACHER, 1817 </div><div>Anatina anatina (Spengler, 1802) </div><div>Anatina cyprinus (Wood, 1828) </div><div>GENUS RAETA GRAY, 1853 </div><div>Raeta plicatella (Lamarck, 1818) </div><div>Raeta undulata (Gould, 1851) </div><div><br></div><div>Family Mesodesmatidae Gray, 1840 </div><div>Subfamily Mesodesmatinae Gray, 1840</div><div><br></div><div>GENUS MESODESMA DESHAYES, 1831 </div><div>Mesodesma (Mesodesma) donacium Lamarck, 1818 </div><div>Mesodesma (Ceronia) arctatum (Conrad, 1831) </div><div>Mesodesma (Ceronia) deauratum (Turton, 1822) </div><div>GENUS AMARILLADESMA HUBER, 2010 </div><div>Amarilladesma mactroides (Reeve, 1854) </div><div><br></div>Discussion<div>Biogeography of the group</div><div>Future research topics</div><div>Acknowledgments </div><div>References </div><div>Figured Captions </div><div>Tables</div><div><br></div>