New species of Anillinus Casey (Carabidae: Trechinae: Bembidiini) from the Southern Appalachians and phylogeography of the A. loweae species group

Abstract

The Anillinus loweae–species group comprises five species occurring in the southern Appalachian Mountains and adjacent upland terrains in southeastern United States. Three new species are described herein. Two are members of the loweae-group, Anillinus merritti sp. nov. from Great Smoky Mountains National Park (GSMNP) (southeastern Tennessee and western North Carolina) and A. juliae sp. nov., from McMinn County, Tennessee. The third, A gimmeli sp. nov. from GSMNP, is closely allied to them morphologically. Loweae-group species may be distinguished from those of other species groups by the presence of paramedian areas without microsculpture on the head. They occur in forest litter habitats and the group’s distribution extends from Mississippi and Alabama in the south to the French Broad River of North Carolina and Tennessee in the north. Species within the group are distinguished mainly using characters of the male genitalia and to a lesser extent, differences in shapes of female spermathecae, body size, and relative proportions of body parts. A phylogeny of loweae-group species based on analyses of COI gene sequences, in combination with geographic distributions and correlations to likely physiographic isolating mechanisms, allow a hypothetical reconstruction of the biogeographic history of the group. The following major factors affected speciation within the loweae-group: (1) division of former ancestral ranges, due to changes in major drainage systems beginning prior to the onset of Pleistocene glaciation; (2) Pliocene-Pleistocene climate cooling and subsequent dispersal constrained by physical barriers; (3) Early Pleistocene glacial cycles influencing altitudinal stratification among species.