Cytogenetic proof that the brine shrimp Artemia franciscana (Crustacea, Branchiopoda) is found in Argentina

Artemia brine shrimps are commercially important and they have been extensi vely studied. This branchiopod crustacean is extensively used in aquacultur e and other commercial and applied practices. The genus also awakes an incr easing interest worldwide as an experimental model in other basic areas of research such as evolution and cytogenetics. In the present work adult male meiosis and nauplii mitotic cells in two Artemia populations from Argentin a (Mar Chiquita and Las Tunas, Cordoba Province) are analyzed and compared to the reference strains A. franciscana (Great Salt Lake, Utah, USA) and A. persimilis (Salinas Grandes de Hidalgo, La Pampa Province, Argentina). The Mar Chiquita population shows the diploid and haploid numbers characterist ic of A. franciscana, and a regular male meiosis. In the Las Tunas populati on diverse diploid and haploid numbers are encountered, and an irregular me iosis is observed in some individuals. Fluorescent DAPI and CMA banding sho ws bright chromocenters of intermediate size and number in both populations . Cytogenetic and phenotypic data show that the population of Mar Chiquita could be assigned to A. franciscana; the variation found in chromocenter si ze and number reflects an heterochromatin polytypism already observed in th is species. The cytogenetic and morphological traits in Las Tunas populatio n suggest an occasional hybridization between A. franciscana and A. persimi lis.