Scientific Name: Colletes robertsonii Dalla Torre, 1896
Common Name: Robertson s Plasterer Bee
Colletes punctata Robertson, 1891: 62 [♂‚] (nec C. punctata Mocsáry (1877))
Holotype ♂‚. USA, Illinois, Carlinville, 6 July [no year provided], by C. Robertson, on Petalostemon violaceus [INHS no. 2234]
Colletes robertsonii Dalla Torre, 1896: 44 (new name for C. punctata Robertson)
Colletes robustus Swenk, 1904a: 251 [♀,♂‚] [synonymy by Timberlake (1943)]
Syntypes ♀,♂‚. USA, Nebraska, ♀ - Neligh, August 1899, by M. Cary, on Petalostemon, ♂‚ - Dundy Co., June [no year provided], by E.H. Jones [University of Nebraska]
Notes on Type Material: Stephen (1954) examined what he called the holotype of C. robustus from Neligh, Nebraska, suggesting that the ♀ indicated above was examined. Timberlake (1943) indicated that some of the paratypes were at the Citrus Experiment Station, Riverside, California, material from which he made the synonymy with.
Species Notes: Stephen (1954) indicated that the synonymy of C. robustus under C. robertsonii was likely correct (he did not examine the type of C. robertsonii). Timberlake (1943) suggested that it should rank as a subspecies (see Michener 1951), though he later (Timberlake 1951) indicated that he did not have the opportunity to verify the synonymy, which was apparently accepted by Swenk, as cited in Timberlake (1951), and Mitchell (1960).