Evolutionary implications of new Postopsyllidiidae from mid-Cretaceous amber from Myanmar and sternorrhynchan nymphal conservatism.

Nymphs of extinct sternorrhynchan hemipterans are extremely rare, although very important for understanding of evolutionary traits of these insects. A protopsyllidioid nymph, in mid-Cretaceous amber from Kachin, Myanmar, placed in the family Postopsyllidiidae, is the first nymph of this family to be found in the fossil. Postopsyllidiidae previously comprised the sole genus Postopsyllidium with a few species: P. rebeccae, P. grimaldii and P. burmaticum from Kachin amber (Cenomanian) and P. emilyae from Turonian amber of New Jersey. Here, we report a new genus and species of postopsyllid Megalophthallidion burmapteron gen. et sp. nov. (imago) and the first known nymph of the family ascribed to the same genus. An overview of the fossil record of sternorrhynchan nymphs, and the importance of this finding, unlocking a new and complementary window to understanding the evolutionary traits of Protopsyllidioidea and other Sternorrhyncha hemipterans are presented.