Abstract
The final instar larva of Progomphus joergenseni is described and illustrated for the first time based on specimens collected in Rio Negro Province, northem Patagonia, Argentina. Right mandibular molar crest shows an extreme reduction in the number ofteeth with no intermediates between teeth a and b. Anteimal, leg and paraprocts morphology suggest a close relationship with the species included in the Pygmaeus group, but P. joergenseni differs from them because of its larger size and longer anal pyramid.
NSTL