Sexual differentiation in Zygochlamys patagonica (King and Broderip, 1832) (Mollusca, Bivalvia, Pectinidae) in Reclutas bed in Argentinian waters.

BIGATTI, G. & BONARD,A

ASFA

Año: 2000 p. 1 - 21

AbstractZygochlamys patagonica is a gonochoric species of the Magellanic Biogeographic Province (South America) which distributes between 40-200 m depth. A possible existence of protandric hermaphroditism is studied based on histological slides and gonad coloration. A sample of 261 specimens between 30 and 69 mm of total length was obtained in Reclutas bed (Argentine Sea, SW Atlantic) at 104 m depth in January 2000. Sex and maturity stages were microscopically detected using a 8 stages common scale (0-VII) for both sexes. Gonadosomatic index was calculated. Sex proportion for individuals higher than 40 mm SH was 1:1 ; only a few hermaphrodites were microscopically detected. No reabsorption of gametes was observed. The existence of protandry is not demonstrated.