Figure 8 from: Bousquet Y (2012) Catalogue of Geadephaga (Coleoptera: Adephaga) of America, north of Mexico. ZooKeys 245: 1-1722. https://doi.org/10.3897/zookeys.245.3416

Figure 8 - Cychrus tuberculatus (Harris). This species belongs to a genus that contains numerous species in the Palaearctic Region but only two in North America, both west coastal elements. The two species are morphologically very similar and likely sister-species, suggesting that a single ancestral stock crossed Beringia. Stomis and Trechoblemus are other carabid genera well represented in the Palaearctic with a single species each on the West Coast of North America.