Biochemical systematics of the cyprinid genus Notropis—I. The subgenus Luxilus

Population samples for all taxa in the subgenus Luxilus of Notropis were genetically analysed by vertical starch gel electrophoresis to detect protein variability. A total of 38 alleles were resolved at 17 presumptive loci. Protein systems examined included adenylate kinase, aspartate aminotransferase, creatine kinase, calcium-binding proteins, general protein, glucosephosphate isomerase, glycerol-3-phosphate dehydrogenase, lactate dehydrogenase, malate dehydrogenase, phosphoglucomutase, and superoxide dismutase. A phylogenetic analysis of the molecular data allows the recognition of four species-groups: (a) the cornutus group including Notropis albeolus, N. chrysocephalus chrysocephalus, N. c. isolepis, and N. cornutus: (b) the zonatus group including N. pilsbryi and N. zonatus; (c) the coccogenis group including N. coccogenis and N. zonistius; and (d) the cerasinus group comprised of N. cerasinus alone. Notropis cerasinus exhibits little genetic affinity for the cornutus species-group and is most closely related to the coccogenis species-group. Both phenetic and phylogenetic analyses deny specific status to the isolepis form. A further analysis of isozyme variability at the Pgm-A and Gpi-A loci may clarify the relationship between N. cornutus and N. chrysocephalus.