Sperm morphology in Buccinanops monilifer (gastropoda: Nassariidae) form the South western Atlantic Ocean.

GIMÉNEZ, J.

Cambridge

Congreso; 7th Congress of The European Malacological Societies; 2014

The Malacological Society of London

Buccinanops monilifer  (Kiener, 1834), endemic in the south-western Atlantic Ocean, is widely distributed in shallow waters up to 50 m deep, from Rio de Janeiro in Brazil (23º8´S) to San Matías Gulf (42º8´S) in Patagonia. In Mar del Plata (Buenos Aires Province). B. monilifer lives in subtidal sandy bottoms of temperate waters. It is usually collected with bottom trawling nets between 5 and 20 m in depth. Ultrastructure of the spermatozoa is a useful tool to know about gastropod phylogeny. We used transmission electron microscopy to study the structure of mature spermatozoa and paraspermatozoa from B. monilifer and compared them with those of other caenogastropoda, particularly other neogastropods. The spermatozoa of B. monilifer contained an elongated nucleus capped by a conical acrosome with an anterior extension. The nucleus is filiform with a complete and long invagination and contains a centriolar derivative. The mid-piece region consists on an axoneme sheathed by helical mitochondrial elements. The flagellum exhibited the typical 9+2 microtubule structure (9 double outer tubules + 2 single central tubules). The parspermatozoa of B. monilifer are vermiform. They contain 2 axonemes, numerous oblong dense vesicles, numerous less dense vesicles, and mitochondria. Most of the euspermatozoal features of B. monilifer are also observed in many neogastropods, with exception of the numbers of axonemes in the parasperm.