THE OLDEST PREDACEOUS WATER BUGS (INSECTA, HETEROPTERA, BELOSTOMATIDAE), WITH IMPLICATIONS FOR PALEOLIMNOLOGY OF THE TRIASSIC COW BRANCH FORMATION

The Triassic Cow Branch Formation (230 – 220 Ma) of Virginia and North Carolina preserves the earliest known fauna of freshwater insects. From this deposit, a new genus and species of predaceous water bugs, Triassonepa solensis n. gen. n. sp., is described based on ~36 adult specimens and 51 nymphs. This species is the oldest known member of the extant family Belostomatidae. It is placed in a new genus based on the unique structure of the raptorial foreleg, in which the tarsus is elongate and opposed to the tibia + femur. The species assemblage preserved in the Cow Branch Formation was used to describe the paleoenvironment of this Late Triassic deposit. Due to the exclusive preservation of terrestrial adult insects and surface-dwelling aquatic insects, in addition to the geochemistry of the deposit, it is likely that the Cow Branch Formation was a saline, alkaline, rift valley lake.