Macromia illinoiensis georgina: subspecies or hybrid

Since the discovery of Macromia georgina by Selys in 1878, many have considered these colorful flyers to be a subspecies of Macromia illinoiensis (Walsh, 1862), such that the two taxa are considered to be Macromia illinoiensis illinoiensis (Walsh, 1862) and Macromia illinoiensis georgina. Indeed the transition zone between the two subspecies, as well as most morphological work supports this theory; however some have suggested that hybridization of the swift river cruiser and its sister species Macromia georgina has resulted in the Macromia illinoiensis georgina morphotype. If this is in fact the case and Macromia illinoiensis and Macromia georgina are interbreeding, then under the Biological Species Concept the two should be considered one species. To test this hypothesis, I have used the mitochondrial COI and nuclear H3 protein coding genes, and analyzed them with maximum likelihood. I will discuss the results of this study with respect to present distributions.