Sperm ultrastructure in two species of Brachidontes (Bivalvia, Mytilidae) from the Southwestern Atlantic Ocean

TORROGLOSA, M. E.; GIMÉNEZ, J.

JOURNAL OF THE MARINE BIOLOGICAL ASSOCIATION OF THE UNITED KINGDOM

CAMBRIDGE UNIV PRESS

Lugar: Cambridge; Año: 2015 vol. 95 p. 991 - 998

0025-3154

Brachidontes rodriguezii and Brachidontes purpuratus have a widegeographic distribution along the Argentinean coast. Both species areabundant in the intertidal area of rocky shores.We used transmission electron microscopy to study the spermatogenesis ofB. rodriguezii and the structure of mature spermatozoa from B. rodrigueziiand B. purpuratus.Our results show that spermatogenesis in B. rodriguezii is very similar tothat reported in other mytilids. The spermatozoa of both Brachidontes areof the primitive or ect-aquasperm type showing a spherical nucleus cappedby a conical acrosome with an anterior extension. The chromatin waselectron-dense, homogenous and compact. The mid-piece region consistedof 5 spherical mitochondria grouped in a ring around a pair of shortcylindrical centrioles. The flagellum exhibit the typical 9+2 microtubulestructure. Studies of spermatozoa ultrastructure are considered an usefultool in bivalve phylogeny. Characters in the spermatozoa morphology ofthese two species were observed and a brief discussion about the spermmorphology along the distribution of both species was done. We suggestthat the acrosome complex present the most significant differencesbetween both species.