MACNBR   00242
MUSEO ARGENTINO DE CIENCIAS NATURALES "BERNARDINO RIVADAVIA"
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Sexual Dimorphism in the shells of the South-Western Atlantic Gastropod Olivella plata (Ihering, 1908) (Mollusca: Olividae)
Autor/es:
PASTORINO, G.
Lugar:
Anveres, Bélgica
Reunión:
Congreso; 16th International Congress of UNITAS MALACOLOGICA y World Congress of Malacology,; 2007
Institución organizadora:
Unitas Malacologica
Resumen:
Most known cases of sexual dimorphism in molluscs are based on size differences. A remarkable case of structural sexual dimorphism recorded during a revision of the genus Olivella from Argentine waters is presented. Over 200 specimens of Olivella plata (Ihering, 1908) were collected at Villarino (42°24’S-64°15’W) in Golfo San José and Punta Pardelas (42°37’S-64°15’W) in Golfo Nuevo, both localities from Chubut province, northern Patagonia. Each live specimen collected was sexed based on the presence of penis and the pedal gland. Female shells are easily recognised as they show an anterior wide vertical groove, adjacent to the parietal callus and the pillar structure. The groove is not on the same plane as the aperture, i.e., it runs approximately at right angles to the apertural plane. Therefore, it is clearly visible in lateral view and not quite so in apertural or adapertural views. The groove curves adaxially at the tip of the also curved pillar. Male shells are distinguished because there is no groove but a continuation of the parietal callus which, apparently “infills” the groove described for the female shells. The existence of such a structure, only present on the females of O. plata, may have helped the animal glue the capsules to the apertural side of the shell, or else may have been at least related to the process of laying capsules.