Morphology, Classification, and Antiquity of Melittosphex Burmensis (apoidea: Melittosphecidae) and Implications for Early Bee Evolution

Melittosphex burmensis (Melittosphecidae) is an important apoid fossil from middle Cretaceous (,100 Ma) amber from Myanmar (Burma). Melittosphex exhibits a combination of wasp and bee features making it an important transitional form linking bees with crabronid wasps. The presence of branched hairs suggests that it was a pollen-collector and many aspects of the morphology suggest that it is more closely related to bees than to any fossil or extant group of wasps. Here we report additional morphological information on Melittosphex burmensis. This specimen remains the earliest body-fossil evidence that pollen-collecting Apoidea (bees) were present approximately 20 million years after the origin of the eudicots (,120 Ma), the major angiosperm lineage with extensive reliance on bee pollination.