Linking Acrosome Size and Genetic Divergence in an Inter-Oceanic Mussel from the Pacific and Atlantic Coasts: A Case of Incipient Speciation?

In recent years, advances in analyses of the sperm morphology and genetics of have allowed to two evolutionary scenarios for this mussel to be suggested: (1) the scenario of cryptic species and (2) the scenario of incipient or in progress speciation. For a better understanding of the evolutionary history of , we performed extensive sampling along a latitudinal gradient of ca. 7180 km of coastline-from the Southern Pacific Ocean to the Atlantic Ocean-and we delved deeper into the sperm morphology of , exploring its association with the phylogeny and population genetics to determine whether the variability in sperm traits between the northern and southern regions was a signal of cryptic or incipient species.

Notes on Mesocapromys sanfelipensis (Rodentia: Capromyidae) from Cuba.

The San Felipe Hutia, Mesocapromys sanfelipensis, is one of the most endangered species of rodents in the world, and little is known about its ecology, evolution, and ancient distribution. At present, this hutia has been found only in its type locality, Cayo Juan Garcia, a cay in the southwest Cuban insular platform. Here we report for the first time a well preserved fossil skull referred to this species, collected in Cueva del Indio, Mayabeque province, western Cuba.

Gametogenesis and nucleotypic effects in the tetraploid red vizcacha rat, Tympanoctomys barrerae (Rodentia, Octodontidae).

Nucleotypic effects link DNA content with nuclear size and cell dimensions of reproductive cells in polyploid organisms. We studied the gametogenesis of the allotetraploid rodent Tympanoctomys barrerae, aiming to determine these effects in reproductive cells. The species' cofamily members, Octodon degus and Spalacopus cyanus were used as control.