Phylogeography and Population Genetics of the Kentucky Endemic Cave Beetle Genus Neaphaenops Jeannel (1920) (Coleoptera: Carabidae: Trechini)

ABSTRACT Cave beetles are an excellent group for studying evolutionary history and speciation within cave habitats. However, they are underrepresented in such research, particularly in North America, a hotspot of cave biodiversity, where beetles account for a significant proportion of documented taxa. This study aims to elucidate the evolutionary history and possible connectivity or barriers to gene flow among populations of the central Kentucky endemic cave beetle, Neaphaenops tellkampfii (Erichson), and to test the validity of four proposed subspecies. We collected specimens from 62 caves, extracted DNA, and sequenced 1169 bp of the Cytochrome C Oxidase Subunit I (CO1) gene, resulting in 36 phylogenetically informative sites for the ingroup. Using this CO1 data, we constructed Bayesian, Maximum Likelihood, and Parsimony phylogenetic trees and also visualized the genetic structure. All the analyses illustrated two distinct southern and northern mega‐populations of this beetle, separated by the Barren River. Based on molecular evidence, here we propose a new concept that the four morphologically defined subspecies should be considered invalid. The three northern subspecies: N. t. tellkampfii (Erichson), N. t. viator Barr, and N. t. henroti Jeannel should be recognized as the single species N. tellkampfii (Erichson), while the southern subspecies N. t. meridionalis Barr should be raised to species level as N. meridionalis Barr, New Status. This study also discovered 26 new Neaphaenops populations. High genetic similarity was observed within each clade, potentially indicating a high level of historical or recent interconnectivity among the caves within the Mississippian Plateau that facilitates underground dispersal and gene flow. Together, our study shows that Neaphaenops or other cave beetles can serve as a biological model for studying speciation, gene flow, evolutionary history, and connectivity within cave systems.