Gene flow, morphology, and taxonomic revision of cave-obligate Hesperochernes pseudoscorpions

Abstract

Pseudoscorpions are small predatory arthropods that are found in surface and subterranean habitats. Subterranean habitats such as caves tend to harbor pseudoscorpion species with highly restricted gene flow and high degrees of endemism. Species described in the genus Hesperochernes contradict this pattern. To investigate gene flow and taxonomically evaluate cave-obligate species in this genus located in eastern North America, an extensive field sampling effort was made that included four major karst regions, permissions to collect in ten states, included over 100 caves, and spanned a distance of over 1000 km. Molecular data were acquired through DNA extraction followed by reduced representation genomic sampling using the 3RAD variant method of RADseq. Population genetic analyses revealed extensive gene flow across putative biogeographic barriers to a nonvolant cave-restricted arthropod. To demonstrate the efficacy and applicability of 2D geometric morphometrics to study of pseudoscorpion morphology, landmarks were developed and assessed through an examination of sexual dimorphism in adult females and males of the chernetid pseudoscorpion Hesperochernes mirabilis collected from a large population found in Oaks Cave, Tennessee. Combining the results of population genetic analyses and the utility of this new 2D geometric morphometrics tool for pseudoscorpions, the three described species were revised and redescribed, with the most senior name, Hesperochernes mirabilis, taking precedence over its two new junior synonyms, Hesperochernes holsingeri and Hesperochernes occidentalis.