Abstract

The Chilean-Peruvian scallop, Argopecten purpuratus, is the southernmost representative of the genus and has become an aquaculture commodity in Chile as a result of 20 y of culture practice promotion after natural beds were almost exhausted by overexploitation. Chromosome preparations of A. purpuratus D-larvae from three samples, two from commercial hatcheries, and one from the few remaining wild populations were subjected to karyotype analysis by the usual measurements of chromosome pairs, Ag-NOR staining, as well as by the Hoechst 33258/Actinomycin D counterstain and restriction endonuclease banding techniques. The species has a modal diploid number of 2n = 32, and the karyotype consists of 11 pairs of telocentric anal five pairs of subtelocentric chromosomes, NF = 32. The banding techniques, attempted for the first time in the species, served as a good complement for identifying a number of homologous chromosomes. The NOR was located terminally on the short arm and in the pericentromeric region in three chromosome pairs. The Hoechst 33258/Actinomycin D counterstain revealed tiny fluorescent heterochromatic areas in the centromeric region of chromosome pairs 1, 2, 4, 5, 6, 7, 8, 9, 11, 15, and 16, whereas a quenching zone was observed in chromosome pair 6. Endonuclease restriction banding revealed pericentromeric and telomeric bands in one chromosome pair (AluI) and interstitial bands in other two chromosome pairs (HaeIII). The karyotype and banding pattern provided in this work are likely to help an industry seeking for improved stocks. Such information will be also valuable for further investigating both intra- and interspecific genomic relationships in the Chilean Pectinids, where the number of species karyologically screened is still very limited.