Andrena (Rhacandrena) robertsonii Dalla Torre 1896

= Andrena (Gonandrena) dreisbachi Mitchell, 1960: 230 (Michigan holotype; Fig. 6C).

Holotype. ♀ USA: Michigan: Roscommon Co.: 5 Jun. 1955, R.R. Dreisbach (NMNH: 75177). Synonymy by LaBerge (1977).

County records: Cheboygan, Ionia, Isabella, Lapeer, Lenawee, Livingston, Macomb, Missaukee, Newaygo, Osceola, Ottawa, Roscommon, Shiawassee, Van Buren, Washtenaw.

Notes. Andrena robertsonii is challenging to distinguish from its apparent sister species A. brevipalpis Cockerell (LaBerge 1977), which also occurs in Michigan. Mitchell identified specimens of A. robtersonii at MSUC were found to be be A. brevipalpis upon reexamination by JG. It is known Mitchell (1960) misapplied the name leading him to redescribe true robertsonii as dreisbachi (LaBerge 1977) .