This study describes a new subspecies of Cicindela limbata Say, C. l. nogahabarensis, from the Nogahabara Sand Dunes of the Koyukuk National Wildlife Refuge, Alaska, on the basis of its distinct maculation pattern and results of mitochondrial DNA (mtDNA) analysis. The maculation pattern of this new subspecies is most similar to and overlaps slightly with that of C. l. labradorensis Johnson from Newfoundland, the subspecies from which it is most distant geographically. Results of the analysis of 1,181 bp of mtDNA (partial cob and nad1-rrnL regions) revealed unique haplotypes supporting C. l. nogahabarensis as a distinct taxon. Geographic clade analysis revealed significant patterns of nonrandom haplotype distribution consistent with postglacial geographic isolation between C. l. nogahabarensis and all other C. limbata. Strong support for the monophyly of C. l. nogahabarensis was retrieved using various tree construction methods. Parsimony analysis and Bayesian methods recovered topologies that placed C. l. nogahabarensis and C. l. labradorensis within a group including all other C. limbata and two other species of the martima group. Under the phylogenetic species concept, unique haplotypes diagnose C. l. nogahabarensis as a separate taxon from topotypical C. limbata. Likewise, the population of C. l. labradorensis that was once thought to be an accidental introduction also was recovered as diagnosably distinct from C. l. limbata. This is the first description of a tiger beetle endemic to Alaska, and both groups demonstrate the occurrence of clearly divergent groups of beetles even in recently glaciated areas.