A remarkably new basal wasp with uniquely transformed forewing in mid-Cretaceous Burmese amber (Hymenoptera, Syspastoxyelidae)

A new genus and species of Syspastoxyelidae, Striaexyela longicornis gen. et sp. nov., is described and illustrated from mid-Cretaceous Burmese amber. Its diagnostic characters are based on the elongated first flagellomere, saw-like ovipositor, and the forewing with contracted proximad venation, abundant longitudinal striae on the wide veinless outer membrane and completely sclerotized pterostigma, which share multiple primitive plesiomorphic traits with xyelid-like groups. Our results provide some high insights into the understanding of morphological changes and the diversity of lower hymenopterans in the Mesozoic.