Two new dragonflies from the Lower Cretaceous deposits of West Mongolia (Anisoptera: Sonidae fam. nov., Corduliidae)

Sona nectes gen. n., sp. n. (Sonidae fam. n.) and Eocordulia cretacea gen. n., sp. n. (Corduliidae; Gomphomacromiinae), based on ca 300 specimens from Lower Cretaceous localities in West Mongolia, are described and illustrated. The material is deposited in the Institute of Palaeontology, USSR Academy of Sciences, Moscow. Sonidae fam. n. is classified as being closer to Gomphidae than to other Aeshnoidea; some specific features of sonid larvae are considered as adaptations to a nectonic mode of life. Some aspects of the new taxa, ecology, geological and palaeogeographical distribution are briefly discussed.