Three new species from the Middle Jurassic of China provide insights on wing spots diversity of Bittacidae (Insecta: Mecoptera)

Three new species, Antiquanabittacus punctatus Yu, Ren, Lin and Yang sp. nov., Composibittacus retroflexus Yu, Ren, Lin and Yang sp. nov. and Formosibittacus multifarius Yu, Ren, Lin and Yang sp. nov., with special wing spots are described and assigned to Bittacidae, based on well-preserved specimens from the Middle Jurassic of China. Antiquanabittacus punctatus sp. nov., the earliest fossil record of Antiquanabittacus, shows new genital characteristics that enhance our understanding of the early morphology of hangingflies. Two morphological types of wing spots are categorized by summarizing all fossil records of Bittacidae, which can be beneficial to classifications and identifications in species level. Wing spots of Type 1, disturbing the overall outline of insect body, and wing spots of Type 2, simulating the spots of light through leaves, may be conducive to conceal hangingflies from predators and improve their capability to ambush preys.