Species boundaries of Pardosa concinna and P. lapponica (Araneae: Lycosidae) in the northern Nearctic: morphology and DNA barcodes.

The Holarctic Pardosa lapponica (Thorell, 1872) and the Nearctic P. concinna (Thorell, 1877) are the only North American members of the Pardosa lapponica species-group. The morphological similarity between the two species raises the question of whether or not they should be treated as separate species. To examine the boundary between P. lapponica and P. concinna, morphological and genetic variation within and between the species was analysed. Copulatory organ characters of Nearctic specimens were analysed to determine if additional diagnostic characters exist, and the mtDNA COI region was sequenced to look for species-specific variation. Morphometric analysis of copulatory characters in females (e.g. length of median septum) and males (e.g. embolus length) of both species did not reveal diagnostic characters other than the terminal apophysis. No species-specific genetic patterns were found between the two species. The interspecific similarities in morphology and low genetic divergence between Nearctic specimens of P. lapponica and P. concinna contrasts with high genetic divergence between Palearctic and Nearctic specimens of P. lapponica. The results suggest a comprehensive taxonomic revision is necessary for the P. lapponica species-group.