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Augochloropsisand other shiny green Halictinae have had various taxonomic issues and are often misidentified. One prevailing taxonomic issue is thatAugochloropsis metallica(Fabricius) has two subspecies, that have long been recognized as morphologically distinct (Augochloropsis metallica metallicaandAugochloropsis metallica fulgida(Smith), but the subspecies are inconsistently applied in the literature. Here, we review theAugochloropsisof the Midwest and further address theAugochloropsisspecies in the broader United States to resolve the outstanding taxonomic issues with the midwestern species. We provide identification keys and diagnoses for the genera and species of the shiny green Halictinae of the midwestern United States, which includes the generaAgapostemon,Augochlora,Augochlorella, andAugochloropsis. This work results in taxonomic changes toAugochloropsis.Augochloropsis sumptuosa(Smith) is split into two species, with the nameAugochloropsis sumptuosaretained for the eastern form, andAugochloropsis humeralis(Patton),stat. nov., reinstated for the western form.Augochloropsis metallicais split into five species, with two of those species occurring in the midwestern United States:Augochloropsis metallicaandAugochloropsis viridula(Smith),stat. nov.Examination of the holotype ofAugochloropsis fulgida(Smith) revealed that it does not agree with the prevailing concept ofAugochloropsis metallica fulgida; it is reinstated asAugochloropsis fulgida,stat. nov., but is currently known only from the holotype female from Florida.Augochloropsis cuprea(Smith), long considered to be a synonym ofAugochloropsis metallica, is also distinct, and we are reinstatingAugochloropsis cuprea,stat. nov., though the range of this species is unclear. We further recognizeAugochloropsis fulvofimbriata(Friese),stat. nov., from South and Central America, as distinct. These changes result in a total of threeAugochloropsisspecies in the Midwest and seven named species in the United States. We are aware of additional species from the southern and southwestern United States that are undescribed, and we highlight additional taxonomic work that remains to be done.

The ability to transport pollen from flowers back to the nest represents a key innovation in the evolution of bees from predatory wasp ancestors. Currently, the origin and evolution of pollen transport remains unsettled. Older hypotheses proposed that crop transport was the original mode of pollen transport, but more recent molecular phylogenies have cast doubt on that view. Instead, more recent hypotheses contend that external transport of dry pollen is ancestral in bees. Here, I propose a new hypothesis to explain the origin and subsequent evolution of pollen transport in bees. I propose that pollen transport arose from adult pollen-feeding behavior and that internal transport of pollen is ancestral in bees. This then led to the evolution of external moist transport, which first required a transition step whereby pollen is temporarily accumulated on the venter on a patch of specialized hairs. Finally, external glazed and dry transport evolved from external moist pollen transport, and the evolution of dry transport led to changes in the location of scopae from the original location on the hind tibia and basitarsus. I illustrate many of these hypothetical evolutionary steps using modern-day bee behavior as an example, with a particular focus on the bee Perdita tortifoliae. Examination of the evolution of pollen transport of pollen wasps (subfamily Masarinae) reveals that they have undergone a parallel evolutionary change. Overall, I lay out a broad hypothetical framework to explain the origin and subsequent evolution of pollen transport in bees. This marks a return to the earlier hypothesis that crop transport is ancestral, and it also represents the first in-depth hypothesis to explain how external transport of moistened pollen could have evolved. The evolutionary history of bees has many implications for the biology of bees in the present day, and I lay out a number of predictions that could help confirm or refute my hypotheses.

Pollen is the primary protein and nutrient source for bees and they employ many different behaviors to gather it. Numerous terms have been coined to describe pollen gathering behaviors, creating confusion as many are not clearly-defined or overlap with existing terms. There is a need for a clear yet flexible classification that enables accurate, succinct descriptions of pollen gathering behaviors to enable meaningful discussion and comparison. Here, we classify the different pollen gathering behaviors into two main classes: active and incidental pollen collection. Active pollen collection is subdivided into six behaviors: scraping with the extremities, buzzing, rubbing with the body and/or scopae, rubbing with the face, tapping, and rasping. In addition to the active and incidental pollen gathering behaviors, many bees have an intermediate step in which they temporarily accumulate pollen on a discrete patch of specialized hairs. Each behavior is described and illustrated with video examples. Many of these behaviors can be further broken down based on the variations found in different bee species. Different species or individual bees mix and match these pollen collecting behaviors depending on their behavioral plasticity and host plant morphology. Taken together, the different behaviors are combined to create complex behavioral repertoires built on a foundation of simple and basic steps. This classification sets the groundwork for further research on various topics, including behavioral plasticity in different species, comparisons between generalists and specialists, and the relative effectiveness of different pollen gathering behaviors.

A systematic study of Perdita subgenus Procockerellia Timberlake and the related subgenus Allomacrotera Timberlake results in the synonymy of the latter with the former, and two specific synonymies: Perdita (Hexaperdita) glamis Timberlake is a junior synonym of Perdita (Procockerellia) stephanomeriae Timberlake, while Perdita (Procockerellia) brachyglossa Timberlake is a junior synonym of Perdita (Cockerellia) imbellis Timberlake. Perdita (Procockerellia) moldenkei Timberlake is moved to subgenus Cockerellia Ashmead. A revised subgeneric diagnosis and key to the three included species are provided. Diagnoses of species are updated with novel characters; distributions and biological data are expanded. A gynandromorph of P. (Procockerellia) moabensis Timberlake, the first known in the genus Perdita, is reported.

International audience; AbstractPurposeful transport of pollen represents a key innovation in the evolution of bees from predatory wasps. Most bees transport pollen on specialized hairs on the hind legs or ventral metasoma in one of three ways: moist, dry, or “glazed,” which combines dry and moist transport. The evolutionary pathway among these three transport modes is unclear, though dry transport has been hypothesized to be ancestral. We address this hypothesis using museum specimens and published records of the bee genera Perdita (Andrenidae) and Hesperapis (Melittidae), two distantly related groups whose pollen transport modes appear to have converged. Most species in both genera transport moistened pollen; glazed and dry transport are limited to derived clades of specialists on floral hosts in Asteraceae and Onagraceae, with specialization on Asteraceae associated with more elaborate scopal hairs. The associations between transport mode, host plant, and hair type may be due to the sticky pollenkitt of asteraceous pollen grains and the viscin threads of Onagraceae pollen, which provide alternates to the binding properties of nectar. These findings suggest that the hypothesis that dry transport is ancestral in bees should be reexamined.

Perdita subgenus Heteroperdita Timberlake, a distinctive subgenus of 22 species from the southwestern United States and adjacent Mexico, all specialists on Tiquilia (Boraginaceae), is revised. Nine new species are described: Perdita ( Heteroperdita ) desdemona Portman, sp. n., P . ( H .) exusta Portman & Griswold, sp. n., P . ( H .) hippolyta Portman & Griswold, sp. n. (male previously incorrectly described as P. pilonotata Timberlake), P . ( H .) hooki Portman & Neff, sp. n., P . ( H .) nuttalliae Portman, sp. n., P . ( H .) prodigiosa Portman & Griswold, sp. n., P . ( H .) sycorax Portman, sp. n., P . ( H .) titania Portman & Griswold, sp. n., and P . ( H .) yanegai Portman, sp. n. The following sexes are associated and described for the first time: the male of P . ( H .) frontalis Timberlake, 1968, the female of P . ( H .) optiva Timberlake, 1954, and the true male of P . ( H .) pilonotata Timberlake, 1980. Perdita ( H .) fasciatella Timberlake, 1980 is proposed as a junior synonym of P . ( H .) sexfasciata Timberlake, 1954. A neotype is designated for P . ( H .) pilonotata Timberlake, 1980. Two species in particular, P. prodigiosa and P. pilonotata , are sexually dimorphic with distinctive ant-like males. Information is presented on floral relationships, phenology, and geographic distribution. Identification keys for males and females are provided.

The monotypic Perdita subgenus Xeromacrotera Timberlake is currently known only from the male sex. Here, the female of Perdita ( Xeromacrotera ) cephalotes (Cresson, 1878) is associated, resulting in two new junior synonyms of P . ( X .) cephalotes : Perdita ( Procockerellia ) excellens Timberlake, 1958, new synonym and Perdita ( Cockerellia ) autumnalis Timberlake, 1977, new synonym. The true number of maxillary palpi are reported, and updated subgeneric and species diagnoses are provided. In addition, Perdita boharti Portman & Griswold, new name, is designated as a replacement name for the primary junior homonym P. bohartorum Parker, 1983 (not P. bohartorum Timberlake, 1956) and is assigned to the related subgenus Cockerellia Ashmead.

Although Megachile Latreille (leafcutter bees) are well known for their diverse nesting habits, records of the genus nesting in live plants are rare. Here, we report the widespread Megachile (Megachile) montivaga Cresson nesting in live thistle (Cirsium neomexicanum Gray), the first explicit record of this behavior in the Nearctic.