An unusual new lineage of sawflies (Hymenoptera) in Upper Cretaceous amber from northern Myanmar

Abstract

A peculiar new lineage of sawflies (‘Symphyta’) is described and figured from a female beautifully preserved in Upper Cretaceous (Cenomanian) amber from northern Myanmar. Syspastoxyela rhaphidia Engel and Huang, gen. et sp. nov., shares many plesiomorphic features with the primitive Xyelidae, †Xyelotomidae, and †Xyelydidae such as enlarged and thickened first flagellomere succeeded by a series of thinner and shorter flagellomeres, absence of a transverse mesoscutal sulcus, multiple preapical spurs, and two protibial spurs among other traits. However, the new lineage has an apomorphically contracted forewing venation, lacks a subcostal vein, has a single marginal cell, and lacks crossvein 1r-rs, and thus it is segregated into a new family, Syspastoxyelidae Engel and Huang, fam. nov. The phylogenetic affinities of the new family are discussed and a position near Pamphilioidea or Pamphilioidea + Unicalcarida is advocated.