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Abstract

Limnic sediments from late Pliocene of Willershausen (Harz, Germany) yielded representatives of two orders of insects, which hitherto have not been recorded there: Megaloptera and Plecoptera. Sialis strausi n. spec. (Megaloptera, Ins.) in its larval form is one of the most common fossils of the layer: hundreds of fossils are found, of which the mandibles (fig. 2 a) and the Malpighi tubes (fig. 2c, d) are significant. One fore wing (fig. 3) of an imago has also been found. According to what is known about the ecology of recent lake-dwelling Sialis-larvae, the numerous fossils of two-year old larvae indicate that the place of their fossilisation has once been the floor of a lake of more than 10 m of depth. Brachyptera schmidti n. spec. (Plecoptera, Ins.) is represented by one female imago (fig. 4, 5). Their position in the sediment indicates, that they submerged and drowned in a nearby brook and have been drifted into the lake, where their fossilisation took place.