A new species of the previously monotypic Neotropical cleptoparasitic bee genus Rhynostelis, with notes on Rhynostelis multiplicata (Hymenoptera: Megachilidae)

A new species of the cleptoparasitic bee genus Rhynostelis Moure & Urban (Megachilidae: Anthidiini) from the Amazon rainforest in Brazil is described and figured. Until now, Rhynostelis multiplicata (Smith) was the only known species in the genus. Females of R. xavieri Mahlmann, new species, can be easily recognized by the larger protuberance on the base of each mandible and the basal projection of the clypeus, which is larger and flat, resembling a bird’s upper beak. Taxonomic notes are also provided for R. multiplicata and an update of occurrence records for the genus is given