Subgeneric classification and biology of the leafcutter and dauber bees (genus Megachile Latreille) of the western Palearctic (Hymenoptera, Apoidea, Megachilidae)

A new identification key is presented for the western Palearctic subgenera of the bee genus Megachile. In addition, the species composition of each subgenus is discussed, and for large subgenera, species groups are delineated to facilitate future taxonomic treatment. The nesting biology and floral associations of each subgenus are briefly reviewed. Lectotypes are designated for Megachile albocincta Radoszkowski, M. genalis Morawitz, M. hirsuta Morawitz, M. inornata Walker, M. luteipennis Friese, M. mandibularis Morawitz, M. melanogaster Eversmann, M. orientalis Morawitz, M. picicornis Morawitz, M. pilicrus Morawitz, M. sedilloti Pérez, M. thevestensis Ferton, M. vestita Giraud (=M. giraudi Gerstäcker) and M. villipes Morawitz. In addition, the following taxonomic changes are proposed: the subgenus Paracella is synonymized with the subgenus Anodonteutricharaea (syn. n.); three species, Megachile breviceps Friese, M. luteipennis and M. algira Radoszkowski are excluded from the Palearctic fauna as they were likely based on mislabeled specimens; M. luteipennis is newly placed in synonymy with M. dimidiata Smith (syn. n.), and M. algira with M. opposita Smith (syn. n.); M. punctatissima Spinola is considered an incorrect spelling of Stelis punctulatissima (Kirby) and not a valid species-group name. Heriades sinuata Spinola is newly placed in synonymy with H. truncorum (Linnaeus) (syn. n); M. boops Friese is transferred to the genus Hoplitis (comb. n.) and placed in synonymy with Hoplitis tigrina (Morawitz) (syn. n.); M. pyrsa Vachal is transferred to the genus Prodioxys (comb. n.) and placed in synonymy with Prodioxys carnea (Gribodo) (syn. n.); Stelis megachiloides Alfken is transferred to the genus Megachile (comb. n.) and placed in synonymy with M. marginata Smith (syn. n); M. larochei Tkalců and M. lanigera Alfken are placed in synonymy with M. albohirta (Brullé), M. albocincta Radoszkowski with cyanipennis Guérin-Méneville, M. rhodosiaca Rebmann and M. heinrichi (Tkalců) with M. doriae Magretti, M. vicina Morawitz with M. giraudi, M. picicornis Morawitz and M. albocincta Pérez with M. marginata, M. esseniensis (Pasteels) with M. maxillosa Guérin-Méneville, M. sexmaculata Alfken, M. sexmaculata thracia Tkalců and M. pilicrus flavida Zanden with M. melanogaster, M. transitoria Benoist with M. parietina (Geoffroy), M. judaea (Tkalců) with M. pasteelsi (Zanden), M. cyrenaica Schulthess, M. fumosa Alfken and M. fulvocrinita Alfken with M. sedilloti, M. insignis Zanden with M. soikai Benoist, M. mavromoustakisi Zanden with M. troodica Mavromoustakis and M. semipleta Cockerell with M. versicolor Smith (syn. n.). Megachile rhodoleucura Cockerell is reestablished as a valid species (stat. rev.). Megachile posti Mavromoustakis is considered as a valid species (stat. n.) and not as a subspecies of M. basilaris Morawitz. Megachile calloleuca Cockerell is newly placed into the subgenus Megachile, M. inornata, M. thevestensis, M. troodica into the subgenus Anodonteutricharaea, and M. hirsuta, M. pasteelsi into the subgenus Chalicodoma.