Hidden diversity of small predators; new thorny lacewings from Mid-Cretaceous amber from northern Myanmar (Neuroptera; Rhachiberothidae; Paraberothinae)

Thorny lacewings (Rhachiberothidae) are currently distributed only within Africa, whereas they are prevalent in the fossil record of various Cretaceous ambers across the Northern Hemisphere, with a handful of the fossil records from some Eocene European ambers. Four rhachiberothid species in four extinct genera are known from the mid-Cretaceous amber of northern Myanmar. Here, we report further examples of the remarkable palaeodiversity of this group from the same amber deposit, adding the four new fossil genera and seven new species: Acanthoberotha cuspis gen. et sp. nov., Astioberotha falcipes gen. et sp. nov., Stygioberotha siculifera gen. et sp. nov., Uranoberotha chariessa gen. et sp. nov., Creagroparaberotha cuneata sp. nov., Micromantispa galeata sp. nov. and M. spicata sp. nov. Based on a series of well-preserved specimens, we discuss the fine details of the raptorial forelegs and genital segments, which may be important for elucidating the phylogenetic relationships among genera. Our findings reveal an unexpectedly diverse assemblage of thorny lacewings in the Cretaceous System, highlighting the morphologically diverse rhachiberothids in Burmese amber. The discovery of seven additional rhachiberothid species in Myanmar amber suggests the potential for much higher diversity and abundance of the Cretaceous rhachiberothids than previously documented. Furthermore, morphological variation in the raptorial forelegs was found to be extremely diverse among the Burmese amber paraberothines, especially in terms of the size, number and shape of spines (or spine-like setae) on the inner edges of protibia, and the morphological structure of the probasitarsus.