Populations of two congeneric species of southwestern Atlantic sciaenid fish, Menticirrhus americanus and Menticirrhus littoralis, analysed electrophoretically to detect isoenzyme variability, showed very little genetic variation and a moderately high similarity in their allelic composition. A total of 22 alleles encoded by 17 loci were observed. Interspecific variability were found for the loci G6pdh-A, G6pdh-B, Hbdh-B, Mdh-B and Sod-A. Intraspecific variation was observed only for Mdh-B in M. littoralis. The genetic similarity between M. americanus and M. littoralis (INEI+0.76) is congruent with the high level of morphological similarity showed by these two congeneric species.
Biochemical systematics; Fishes; Menticirrhus americanus; Menticirrhus littoralis; Sciaenidae; Electrophoresis; Isoenzymes; South coast