TAXONOMIC DESCRIPTION OF TIPULIDAE FROM PASSAMARI MEMBER OF THE RENOVA FORMATION

In the Passamari member of the Renova Formation remain well preserved Tipulid fossils dating back to the late Oligocene. These specimens were found in a post Laramide Extensional basin in SW Montana nicknamed the “Fossil Basin.” The Passamari member is a lacustrine environment that has a considerable volcanic ash input. Fossils are found in finely-laminated, fissile "paper shales" and are preserved as organic compressions.

Adult Tipuloidea have wing lengths between 2mm and 40mm and a body length of up to 60mm, have two complete anal veins in their wings, lack ocelli, and have a V-shaped transverse suture on the mesothorax. Differentiation of the Tipulidae relies mostly on wing venation. There are 159 genera and 1610 subspecies of Tipuloidea in the Nearctic region of earth (North America and Greenland).

Sources such as the “Manual of Nearctic Diptera” provide diagrams of wing venation for currently existing species. Comparing those diagrams to the fossils allow for identification of the genus and species. If the species has not yet been identified then a new species will be established.