A new bee genus from the pampas of eastern Argentina, with appended notes on the classification of “ paracolletines ” (Hymenoptera: Colletidae) Author Engel, Michael S. Division of Entomology, Natural History Museum, and Department of Ecology & Evolutionary Biology, 1501 Crestline Drive - Suite 140, University of Kansas, Lawrence, Kansas 66045 - 4415, USA (msengel @ ku. edu). & Division of Invertebrate Zoölogy, American Museum of Natural History, Central Park West at 79 Street, New York, New York 10024 - 5192, USA. Author Gonzalez, Victor H. Undergraduate Biology, and Department of Ecology & Evolutionary Biology, 1200 Sunnyside Avenue, University of Kansas, Lawrence, Kansas 66045, USA (vhgonza @ ku. edu). text Journal of Melittology 2022 2022-01-24 2022 109 1 39 http://dx.doi.org/10.17161/jom.i109.16424 journal article 10.17161/jom.i109.16424 2325-4467 13146121 6C96BAB7-7AF6-4B8B-A2EF-08BD9F3A1344 Packercolletes Engel , new genus ZooBank: urn:lsid:zoobank.org:act: DCEC86F0-889A-43D9-ACE0-AACEC9AB0535 TYPE SPECIES : Leioproctus idiotropoptera Packer, 2006 . DIAGNOSIS: Like Baeocolletes Michener , this genus has 1m-cu entering meeting the first submarginal cell. The middle and hind legs of the male are spectacularly modified (as described by Packer, 2006), and the male mandible is uniquely flatened. Unlike Baeocolletes , the clypeus and supraclypeal area are convex, with the later elevated above the level of the antennal toruli, and with abundant punctures; the metatibial spurs are slender and not strongly arched apically; the inner metatibial spur is pectinate and the outer spur differs from the inner spur; and the pretarsal claws have an inner ramus. Sternum VII of the male greatly resembles that of some Protomorpha Rayment ( e.g ., Protomorpha tarsalis Rayment ), a group in which males also tend to have spectacular leg modifications, but of the hind legs. The other terminalic structures share no resemblance. Protomorpha , however, has three submarginal cells, females with metasomal tergal setal bands, and there is a distinct carina separating the basal area of the propodeum posteriorly from the vertical surface. ETYMOLOGY: The new genus-group name is a combination of Packer, surname of Laurence Packer, esteemed melitologist who discovered the type species, and kollitís ( κολλητής , meaning, “gluer” or “one who glues”). The gender of the name is masculine.