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Evolution of the Radular Apparatus in Conoidea (Gastropoda: Neogastropoda) as Inferred from a Molecular Phylogeny
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Edité par CCSD ; Institute of Malacology -
International audience. The radular anatomy and evolution of the radular apparatus in predatory marine gastropods, superfamily Conoidea, is reconstructed on the basis of a molecular phylogeny, based on three mitochondrial genes (COI, 12S and 16S) for 101 species. A unique feeding mechanism involving use of individual marginal radular teeth at the proboscis tip for stabbing and envenomation of prey at the proboscis tip appeared at the earliest stages of evolution of the group. The initial major evolutionary event in Conoidea was the divergence to two main branches. One is characterized by mostly hypodermic marginal teeth and absence of an odontophore, while the other possesses a radula with primarily duplex marginal teeth, a strong subradular membrane and retains a fully functional odontophore. The radular types that have previously been considered most ancestral, "prototypic" for the group (flat marginal teeth; multicuspid lateral teeth of Drilliidae; solid recurved teeth of Pseudomelatoma and Duplicaria), were found to be derived conditions. Solid recurved teeth appeared twice, independently, in Conoidea-in Pseudomelatomidae and Terebridae. The Terebridae, the sister group of Turridae, are characterized by very high radular variability, and the transformation of the marginal radular teeth within this single clade repeats the evolution of the radular apparatus across the entire Conoidea.
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