Data from: Species delimitation in the ground beetle subgenus Liocosmius (Coleoptera: Carabidae: Bembidion), including standard and next-generation sequencing of museum specimens

The species of subgenus Liocosmius Casey of genus Bembidion Latreille are delimited and documented using DNA sequences from eight genes, morphological data, and geography. The subgenus consists of six known species, three of which are described as new: Bembidion orion Cooper and Maddison (California), B. darlingtonielum Cooper and Maddison (California), and B. cooperi Maddison (New Mexico and Arizona). The group ranges from British Columbia south to Baja California, and east to Colorado and New Mexico, with the centre of diversity in California. DNA from a pinned specimen collected in 1968 was sequenced using an Illumina platform, resulting in accurate data of all eight genes studied. Identification tools and descriptions of each species are provided