Gomphidae (Fig. 52)

This family is represented in Patagonia by four species in two genera: Neogomphus and Progomphus . The Patagonian endemic genus Neogomphus is composed of the Chilean endemics N. bidens and N. molestus as well as N. edenticulatus, recorded on both sides of the Andes; all of them inhabit Nothofagus forests.

Neogomphus molestus apparently prefers rapid rivers, whereas N. bidens prefers large and slow ones. Neogomphus edenticulatus exhibits a wider habitat preference, being the only Patagonian gomphid found at lakes as well as streams and rivers (Carle & Cook 1984). Neogomphus bidens and N. edenticulatus have been recorded in sympatry (Carle & Cook 1984).

The neotropical speciose genus Progomphus is represented only by P. joergenseni, an Andean species recorded from Peru and Bolivia to Argentina and Chile; this species has a scattered distribution restricted to permanent, 1–2 m wide, sandy streams fed by spring waters, being on occasions abundant (e.g. Valcheta stream headings in Somuncura plateau). Described larvae were collected in sandy beds at depths of 30–40 cm. Adults fly along the stream, resting on boulders. (Muzón et al. 2005, 2010; Muzón & Lozano 2011).

All Patagonian gomphid larvae have been described (Needham & Bullock 1943; Belle 1992; Muzón & Lozano 2011). Both genera can be easily separated not just by their different distribution patterns (forest vs. steppe habitats), but by the orientation of the wingpads: widely divergent in Progomphus and parallel in Neogomphus (Fig. 41).