Rhyacophila quadrata n. sp., a new caddisfly (Insecta, Trichoptera) from Eocene Baltic amber

Insects of the order Trichoptera (caddisflies) are represented in Baltic amber by 22 families and comprise about 2% of all inclusions (Wichard & Weitschat 1996). Among these, the genus Rhyacophila (Rhyacophilidae) is a rare taxon presented with six so far known fossil species (Rhyacophila kutscheri Mey, 1988; R. laminata Ulmer, 1912; R. liedtkei Wichard & Caspers, 1991; R. occulta Hagen, 1856; R. palaepolonica Wichard & Caspers, 1991; R. profusa Ulmer, 1912). Herein we present the description of a new fossil species preserved in Baltic amber. The new species presented below is represented by a male imago which is differentiated from all other fossil members of the genus by its square-shaped harpago. Today, Rhyacophila is a very large genus of the Trichoptera which includes approximately 500 known species distributed over the northern hemisphere, reported as far south as the Atlas mountains in northern Africa and ranging southwards towards Java in Indonesia to the Oriental region, and northern Mexico in the Nearctic region (Schmid 1970; Wiggins 2004). It should be interesting to examine the occurrence patterns of Rhyacophila in Eocene amber with respect to modern biodiversity dynamics and biogeographical patterns of the genus. Today, aquatic larvae of Rhyacophila occur in almost all running-water habitats of the northern hemisphere. In the Eocene, however, species belonging to Rhyacophila are exceptional findings. We discuss how far climate change throughout the Cenozoic influenced the biodiversity and distribution of Rhyacophila.