Scientific Name: Megachile rotundata (Fabricius, 1787)
Common Name: Alfalfa Leafcutter Bee
Apis rotundata Fabricius, 1787: 303 
Neotype ♀ [designated by Roberts 1974: 191]. HUNGARY, Simontornya, 12 August [19?]33 [Simontornya Hu. occ. leg. Pillich, 12.8.33 C. can.] [Zoological Museum of Copenhagen]
Apis pacifica Panzer 1798: 16 [♂‚] [synonymy by Panzer 1806: ]
Lectotype ♂‚ [designated by Rebmann 1967: 36]. GERMANY, Noremburg [Berliner Zoologisches Museum [Museum für Naturkunde Berlin]]
Megachile imbecilla Gerstäcker, 1869: 359 [♀] [synonymy by Mocsàry 1881: 19 (with M. pacifica)]
Megachile nadia Nurse, 1903: 546 [♀,♂‚] [synonymy by ?]
Syntypes ♀,♂‚. INDIA, Murree-Kashmir road, between 4000 and 5000 feet 
Much past confusion on the use of Megachile rotundata Fabricius exists, particularly in North America due to an initial misidentification of a non-native species and subsequent use of the name associated with the commercial development of this species (Parker 1975). Hurd (1967) examined the Fabricius collections in Kiel and Copenhagen, and indicated that he did not believe the material in Kiel matched the original description of Apis rotundata; two of the four specimens labelled as A. rotundata were actually species of Osmia, and the other two specimens were damaged, but thought to be specimens of Megachile in the subgenus Eutricharaea (the subgenus M. rotundata is currently placed in). He (Hurd 1967) felt that the single specimen in Copenhagen matched the original description of Fabricius (1787), and designated it as the lectotype of Apis rotundata Fabricius. However, he also indicated that this specimen was not the same species as Megachile rotundata auct. (i.e., not the common species introduced to North America and used for commercial pollination) (Hurd 1967). Roberts (1974) provided a summary of the historic problems with the use of names associated with this material, and petitioned the ICZN to consider Megachile rotundata auct. (i.e., as described by Mitchell (1962) and introduced to North America) to serve as type material for M. rotundata to stabilize the nomenclature, and selected the neotype from Hungary describe above. This decision was accepted by the ICZN in 1977 (ICZN 1977; Roberts 1978) despite some opposition; Parker (1975) suggested (incorrectly it turned out) that the name M. rotundata was only being widely used in the United States (and Canada) where it is used as a commercial pollinator, while M. pacific was being used for this species in Europe (and incidentally, at the Utah Bee Biology and Systematics Laboratory). Megachile rotundata has been applied to this important commercial pollinator ever since (e.g., Donovan 1979), though M. pacifica Panzer still appeared in the Nearctic catalog of Hurd (1979).
Interestingly, Panzer (1798) used Apis rotundata (also later used by Kirby 1802), a homonym Apis rotundata Fabricius, for a species of Anthophora (Apidae) that is now a synonymy of Anthophora bimaculata (Panzer) names in the same work.
Apis pacifica has also created some confusion in addition to that mentioned above. Panzer (1806) was informed that his species (described eight years earlier) was the same as Apis rotundata Fabricius when he sent material to Fabricius for examination; von Dalla Torre (1896) subsequently listed A. pacifica as a synonymy of M. rotundata. Based on the opinion of Mitchell (1962), Rebmann (1967) designated a lectotype for A. pacifica, and indicated that it was the same species as M. rotundata auct. nec Fabricius, lending support to the petition of Roberts (1974). Though Hurd (1979) still recognized M. pacifica (Panzer) as a valid species (albeit one introduced to North America), he mistakenly indicated that the type material was female; Panzer clearly indicated with an illustration that his material were males (though he may have incorrectly recognized them as females). Mocsàry (1881) correctly indicated male type material.
Donovan BJ (1979) The correct names of the megachilid bee introduced for lucerne pollination (Hymenoptera: Megachilidae). New Zealand Entomologist 7(1): 63. https://doi.org/10.1080/00779962.1979.9722333
Fabricius JC (1787) Mantissa Insectorum sistens eorum species nuper detectas adiectis characteribus genericis, differentiis, specificis, emendationibus. Hafniae (Proft) 1. 20 + 348 pp.
Gerstäcker A (1869) Beiträge zur näheren Kenntniss einiger Bienen-Gattungen. Entomologische Zeitung 30: 315-367.
Hurd PD Jr (1967) The identity of Megachile rotundata (Fabricius) and M. argentata (Fabricius) (Hymenoptera: Apoidea). Entomologiske Meddelelser 35: 3-10.
Hurd PD Jr (1979) Superfamily Apoidea. Pgs. 1741-2209. In: Krombein KV, Hurd PD Jr, Smith DR, Burks BD. Catalog of Hymenoptera in America North of Mexico. Volume 2. Apocrita (Aculeata). Smithsonian Institution Press, Washington, DC.
International Commission on Zoological Nomenclature (ICZN) (1977) Opinion 1093 Designation under the plenary powers of a neotype for Apis rotundata Fabricius, 1787 (Insecta: Hymenoptera). Bulletin of Zoological Nomenclature 34(1): 143-146.
Kirby W (1802) Monographia Apum Angliae. II. Ipswich, 388 pp.
Mitchell TB (1962) Bees of the Eastern United States. Volume 2. North Carolina Agricultural Experimental Station Technical Bulletin 152: 1-557.
Mocsàry A (1881) Synonymische Bemerkungen. Entomologische Nachrichten 7(1): 18-20.
Nurse CG (1903) LXXV.—New species of Indian Aculeate Hymenoptera. Annals and Magazine of Natural History, Series 7 11(66): 529-549. https://doi.org/10.1080/00222930308678815
Panzer GWF (1798) Faunae insectorum Germanica initia 55
Panzer GWF (1806) Kritische Revision der Insectenfauna Deutschlands, nach dem System bearbeitet. Nürnberg 2: 244
Parker FD (1975) Comments on "Apis rotundata Fabricius, 1793 (Insecta, Hymenoptera): proposed suppression of lectotype and designation of neotype in accord with Megachile rotundata auct. " Z.N.(S.) 2042. Bulletin of Zoological Nomenclature 32: 82.
Rebmann O (1967) 2. Beitrag zur Kenntnis der Gattung Megachile Latr. (Hym., Apidae): Was ist “Megachile argentata auct.” und “Megachile rotundata auct.”. Entomologische Zeitschrift 77: 168–169.
Roberts RB (1974) Apis rotundata Fabricius, 1793 (Insecta, Hymenoptera): proposed suppression of lectotype and designation of neotype in accord with Megachile rotundata auct. Z.N.(S.) 2042. Bulletin of Zoological Nomenclature 30: 190-192.
Roberts RB (1978) Megachile rotundata (Fabricius), not Megachile pacifica (Panzer), is the name of the alfalfa leafcutting bee (Hymenoptera: Megachilidae). Bulletin of the Entomological Siciety of America 24(3): 392. https://doi.org/10.1093/besa/24.3.392
von Dalla Torre KW (1896) Catalogus hymenopterorum hucusque descriptorum systematicus et synonymicus. Volumen X: Apidae (Anthophilia). Leipzig, Engelmann, 643 pp.
Nesting: Cavity Renter
Pollen Specialization: Polylectic
Wintering Stage: Mature Larva
Distribution: Alberta, British Columbia, Manitoba, New Brunswick, Newfoundland, Nova Scotia, Ontario, Prince Edward Island, Quebec, Saskatchewan
Ecozone: Atlantic Maritime, Mixwood Plains, Newfoundland Boreal, Pacific Maritime, Prairie, Western Interior Basin