Spermatozoa morphology of Brachidontes rodriguezii (d’Orbigny, 1846) (Bivalvia) from South western Atlantic Ocean

TORROGLOSA, M.E.; GIMÉNEZ, JULIANA

Philadelphia

Encuentro; 78 th Meeting of the American Malacological Society; 2012

Brachidontes rodriguezii have a wide geographic distribution along the Argentinean coast from 36º 32´S to Patagonia 42º45´S. Is the most abundant species in the intertidal benthic community associated to rocky shore. In the last years after the growth of the cities along the coast and the introduction of hard substrates as docks, the sandy beaches became a new habitat for this species. Ultrastructural of spermatozoa are a useful tool to know about bivalve phylogeny. We used transmission electron microscopy to study the structure of mature spermatozoa from Brachidontes rodriguezii and compared them with those of other bivalves, particularly other mytilids. The spermatozoa of B. rodriguezii contained a spherical nucleus capped by a conical acrosome with an anterior extension. The chromatin was electron-dense, homogenous and compact. The mid-piece region consisted of 5 spherical mitochondria grouped in a ring around a pair of short cylindrical centrioles. The flagellum exhibited the typical 9+2 microtubule structure (9 double outer tubules + 2 single central tubules). Comparison with another Brachidontes were done.