The images shows a male of the South American pergid sawfly Skelosyzygonia spinipes Malaise. The species is known only from the male. Note the large, spiniform, raptorial hind legs that are unique among sawflies. Males of Aulacomerus buquetii Spinola have also large, raptorial-like hindlegs, but they are not as large and they lack the spines. The hind legs of the female of A. buquetii are normal like in most other sawflies.
So far only a few specimens of Skelosyzygonia spinipes are present in entomological collections, all of them from locations in Brazil. The specimen depicted in the image is housed in the National Museum of Natural History, Smithsonian Institution, Washington, D.C.
Contact: Hymenoptera.ZSM (at) gmail.com