Microsatellite loci for the critically endangered Santa Cruz long-toed salamander (Ambystoma macrodactylum croceum) and other Ambystoma taxa

The imperiled Santa Cruz long-toed salamander (Ambystoma macrodactylum croceum) is a geographically isolated lineage of the long-toed salamander species complex. Recovery of this taxon requires understanding its population genetic structure, which is necessary to identify critical habitat. To assess the population structure of A. m. croceum, I developed primers for 17 microsatellite loci and evaluated their performance. Polymorphism ranged from 3 to 10 alleles per locus, with an average of 6.3 per locus. Mean observed and expected heterozygosity were similar (H (O) = 0.678; H (E) = 0.708), with one locus demonstrating heterozygote deficiency. The performance of these and previously identified microsatellite loci were also characterized for two other long-toed salamander lineages, as well as two other species of Ambystoma. The utility of these markers has similar and overlapping applications for conservation and population genetics studies of other Ambystoma taxa, and will provide a basis for revising the recovery plan for A. m. croceum, particularly for designating corridors among interacting breeding populations and upland areas, and identifying areas where gene flow should be restored.