Two new species ofBembidionare described from river shores in North America. One,Bembidion mimbressp. nov., from the Gila River watershed in the lands of the Mimbres culture in New Mexico and Arizona, is closely related to the widespreadBembidion levigatum. DNA sequences from several linkage groups and morphology provide evidence of the distinctiveness ofB. mimbres. The second,Bembidion corgenomasp. nov., has been the subject of recent genomic and transcriptomic studies. It belongs in theBembidion transversalesubgroup, and occurs from California north to British Columbia, east to Montana and Nevada. TheB. transversalesubgroup as a whole is reviewed, and morphological characters that distinguishB. corgenomafrom the similar and sympatricB. transversaleandB. erosumare 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 withinBembidionfor 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 haplogonumChaudoir. Chromosomes of the new species and their relatives are as is typical forBembidion, with eleven pairs of autosomes and an XY/XX sex chromosome system.
