Morphometric and genetic analysis as proof of the existence of two sturgeon species in the Guadalquivir river

Morphometric and genetic methods were used to identify two sturgeon species, Acipenser naccarii Bonaparte, 1836, and A. sturio Linnaeus, 1758, captured in some of the principal rivers of the Iberian Peninsula, including the Guadalquivir. After measuring 25 Iberian specimens from a fishery and several Spanish and Portuguese museums and applying stepwise discriminant analysis (SDA), four specimens preserved in different museums [two specimens from the Guadalquivir river (EBD-8173 and EBD-8174), one specimen from the Tagus river (MUC1) and one specimen from the Mondego river (MUC46B)], as well as five specimens captured in the Guadalquivir river in the 1940s but not preserved (CM1, CM2, CM3, CM4 and CM5), were identified as A. naccarii. After cloning and characterisation of a satellite-DNA family, HindIII, from A. naccarii genome, its absence from the genome of A. sturio was determined. Using this satellite-DNA as a genetic marker and by means of dot-blotting, we demonstrate that the DNA of the two specimens captured during the mid-1970s in the Guadalquivir river cross-hybridised with HindIII satellite-DNA sequences of A. naccarii. We conclude that A. naccarii is autochthonous to the Iberian Peninsula and is not, as was previously believed, endemic to the Adriatic Sea.