A new peltoperlid stonefly from mid-Cretaceous amber of northern Myanmar (Plecoptera: Peltoperlidae)

Abstract

The eggs of insects are evolving diversely under developmental, morphological, and ecological pressures. Fossil eggs of insects can provide essential biological and evolutionary implications for the related insect groups. Peltoperlidae is a small stonefly family comprising 10 extant genera in two extant subfamilies and only two extinct genera in a fossil subfamily. The phylogenetic relationship between the three subfamilies of Peltoperlidae as well as the generic level phylogeny remain unclear. Herein, a new Cretaceous peltoperlid genus and species, Dewaltoperla edwardi gen. et sp. nov., is reported in Kachin amber from northern Myanmar (98.79 ± 0.62 Ma). The discovery presents the third fossil stonefly of Peltoperlidae, and more importantly, the first fossil eggs for the family. Dewaltoperla is assigned to the extinct subfamily Borisoperlinae and can be distinguished from other fossil peltoperlids by wing venation. The morphological phylogenetic analysis was conducted for all peltoperlid genera for the first time, which identifies Borisoperlinae as a basal group within Peltoperlidae and suggests an evolutionary trend of the egg shape transition from flattened to spherical ones.