76 (2): 215 – 234 18.7.2018 © Senckenberg Gesellschaft für Naturforschung, 2018. A new genus of eucerine bees endemic to southwestern North America revealed in phylogenetic analyses of the Eucera complex (Hymenoptera: Apidae: Eucerini) Achik Dorchin *, 1, 2, Bryan Nicolas Danforth 1 & Terry Griswold 2 1 Department of Entomology, Cornell University, Ithaca, NY 14853, USA; Achik Dorchin * [
[email protected]]; Bryan Nicolas Dan- forth [
[email protected]] — 2 USDA-ARS, Pollinating Insects Research Unit, Utah State University, Logan, UT 84322, USA; Terry Griswold [
[email protected]] — * Corresponding author Accepted 17.iii.2018. Published online at www.senckenberg.de/arthropod-systematics on 29.vi.2018. Editors in charge: Bradley Sinclair & Klaus-Dieter Klass Abstract. The Eucera complex (Apidae: Eucerini), which traditionally included the genus Eucera and a few other related genera comprises a large complex in which generic boundaries have long remained unsettled. Based on comprehensive phylogenetic analyses, a recent study completely reorganized the generic classification of the group. Unexpectedly, both morphological and molecular analyses indicated that the taxon known as the venusta-group of the Eucera subgenus Synhalonia is in fact an isolated early diverging lineage, distantly related to Synhalonia. The only three species currently known in the venusta-group are endemic to arid and semi-arid habitats of the southwestern USA and Baja California in Mexico, and are relatively rare in entomological collections. Here we recognize a new genus: Protohalonia Dorchin gen.n., compare its morphology with related genera, and present a revision and identification keys for the three species included. We reexamine the phylogenetic position of the new genus based on our previously published molecular and morphological datasets, which we supplement with data for the remaining Protohalonia species.