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

Artemia brine shrimps are commercially important and they have been extensively studied. This branchiopod crustacean is extensively used in aquaculture and other commercial and applied practices. The genus also awakes an increasing 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 Argentina (Mar Chiquita and Las Tunas, Córdoba 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 characteristic of A. franciscana, and a regular male meiosis. In the Las Tunas population diverse diploid and haploid numbers are encountered, and an irregular meiosis is observed in some individuals. Fluorescent DAPI and CMA banding shows 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 size and number reflects an heterochromatin polytypism already observed in this species. The cytogenetic and morphological traits in Las Tunas population suggest an occasional hybridization between A. franciscana and A. persimilis.