Shards, sequences, and shorelines: two new species of Bembidion from North America ( Coleoptera, Carabidae)

Two new species of Bembidion are described from river shores in North America. One, Bembidion mimbres sp. nov., from the Gila River watershed in the lands of the Mimbres culture in New Mexico and Arizona, is closely related to the widespread Bembidion levigatwa. DNA sequences from several linkage groups and morphology provide evidence of the distinctiveness of B. mimbres. The second, Bernbidion corgenoma sp. nov., has been the subject of recent genomic and transcriptomic studies. It belongs in the Bembidion transvenale subgroup, and occurs from California north to British Columbia, east to Montana and Nevada. The B.transvenak, subgroup as a whole is reviewed, and morphological characters that distinguish B. colgenoma from the similar and sympatric B. transversals and B. erosum are described and illustrated. DNA sequences of these three species show no consistent differences in 28S, COI, CAD, and Topoisomerase, and a coalescent species delimitation analysis reveals no notable structure within the complex. This is the first known trio of species within Bembidion for which those genes provide no clear signal of species boundaries. A neotype is designated for the one name in the group that lacks a primary type, Bembidium haplogonum Chaudoir. Chromosomes of the new species and their relatives are as is typical for Bembidion, with eleven pairs of autosomes and an XY/XX sex chromosome system.