We studied genetic variation in 107 individuals from 12 Italian populations of the crested newt, Triturus carnifex, by horizontal starch-gel electrophoresis to test the hypothesis of disjunction along the Central Apennine, as has been found in other animals. Twenty-eight presumptive loci were evidenced, 10 of which were monomorphic. Gene diversity was found to be high for salamandrids (mean
... [Show full abstract] percentage of polymorphic loci = 46.4, mean expected heterozygosity = 0.048, mean F(ST) = 0.358) with about two-thirds due to within-population diversity. Both multidimensional scaling and neighbor-joining analyses on genetic distances (mean Nei's D = 0.131) between populations showed that these can be divided into two units, distributed north and south of the Central Apennines, respectively. Within-population gene diversity was found to be lower in the north-cluster, following a pattern of isolation-by-distance; this pattern was not observed in the south. We conclude that historical events (possibly glaciations) divided the populations into the two cited units. The genetic structure of T. carnifex in central and southern Italy somewhat parallels that of T. italicus from the same areas, thus suggesting a common evolutionary pattern of variation.