We obtained and analyzed whole genome shotgun sequences of all 845 species of butterflies recorded from Canada and the United States. Genome-scale phylogenetic trees constructed from the data reveal several non-monophyletic genera and suggest improved classification of species included in these genera. Here, these changes are formalized and 2 subgenera are described: Amblyteria Grishin, subgen. n. (type species Goniloba exoteria Herrich-Schäffer, 1869, parent genus Amblyscirtes Scudder, 1872), and Coa Grishin, subgen. n. (type species Hesperia baracoa Lucas, 1857, parent genus Polites Scudder, 1872). Furthermore, we resurrect 3 genera and 2 subgenera from synonymy, change the rank of 6 currently used genera to subgenus, synonymize 2 genera, transfer 3 (2 resurrected) subgenera and 11 additional species to different genera than those these taxa were assigned to, and raise one name from synonym to species rank. Namely, Hedone Scudder, 1872 and Limochores Scudder, 1872 are valid genera and not synonyms of Polites Scudder, 1872; Pendantus K. Johnson & Kroenlein, 1993 is a valid genus and not a synonym of Electrostrymon Clench, 1961; and Sphaenogona Butler, 1870 and Lucidia Lacordaire, 1833 are valid subgenera of Abaeis Hübner, [1819] (new placement) and not synonyms of Eurema Hübner, [1819]. The following taxa are best treated as subgenera: Mimoides Brown, 1991 of Eurytides Hübner, [1821] (sensu lato); Philotiella Mattoni, [1978] of Euphilotes Mattoni, [1978]; Neominois Scudder, 1875 of Oeneis Hübner, [1819]; Agraulis Boisduval & Le Conte, [1835] of Dione Hübner, [1819]; Copaeodes Speyer, 1877 of Oarisma Scudder, 1872; and Problema Skinner & R. Williams, 1924 of Atrytone Scudder, 1872. Phaeostrymon Clench, 1961 and Saliana Evans, 1955 are junior subjective synonyms of Satyrium Scudder, 1876 and Calpodes Hübner, [1819], respectively. The entire subgenus Erynnides Burns, 1964 is transferred from Erynnis Schrank, 1801 to Gesta Evans, 1953. New genus-species combinations resulting from transfer of species between genera are: Nastra perigenes (Godman, 1900) (not Vidius Evans, 1955); Troyus fantasos (Cramer, 1780), Troyus onaca (Evans, 1955), Troyus aurelius (Plötz, 1882), Troyus marcus (Fabricius, 1787), Troyus diversa (Herrich-Schäffer, 1869), and Troyus drova (Evans, 1955) (not Vettius Godman, 1901); Oligoria percosius (Godman, 1900), Oligoria rindgei (H. Freeman, 1969), Oligoria lucifer (Hübner, [1831]), and Oligoria mustea (H. Freeman, 1979) (not Decinea Evans, 1955). Urbanus alva Evans, 1952 is a valid species and not a synonym of Urbanus belli (Hayward, 1935), new status.
Keywords: biodiversity; classification; genomics; phylogeny; taxonomy.