MOMENTUM AND GHISELINIUS, NEW NEOTROPICAL GENERA OF HUMICOLOUS BEETLES WITH REMARKABLE AND DIVERGENT MOUTHPARTS (COLEOPTERA, DRYOPIDAE)

Two new, related genera of humicolous Dryopidae (Coleoptera) are descr ibed for new species from Central and South America. Momentum, new gen us, is described for six new species from Costa Rica, Panama, Venezuel a, Colombia and Ecuador: Ghiselinius, net: genus, is described for one new species from Colombia. Members of Momentum are characterized by m arked sexual dimorphism, including the greatly modified sensilla beari ng labial palpi of male male, and the wingless and nearly eyeless cond ition of female female . These two genera share a distinctive derived aedeagal structure. Separate generic status is indicated by the mentum and ligula, which are comparatively divergently derived Protoparnus p usillus Hinton, from St. Vincent in the Lesser Antilles, is ii transfe rred to Momentum. Taxonomically and phylogenetically significant featu res are discussed and illustrated with scanning electron micrographs a nd line drawings. A key to the species of Momentum is presented.