“…are an enigmatic and challenging radiation of temperate species that spans the Holarctic region. These genera are associated with Viola larval food plants and have been the subject of numerous systematic (Warren, ; dos Passos & Grey, ; Simonsen, ; Dunford, ; McHugh et al ., ), morphological (Urbahn, ; Barth, ; Williams, ; Simonsen, , ; James, ; Zaman et al ., ) and ecological studies (Boggs, ; McCorkle & Hammond, ; Boggs & Ross, ; Kelly & Debinski, ; Bierzychudek et al ., ; Zimmermann et al ., ; James & Pelham, ; Zaman et al ., ), as well as the focus of recent conservation studies (Shepherd & Debinski, ; Salz & Fartmann, ; Schultz et al ., ; Zima et al ., ; Wells & Tonkyn, ), of which the references here are only a few. Despite this long history of study, a detailed understanding of the patterns and processes of this radiation is hampered by classification and systematic challenges.…”