Arroyo Queñi near Lago Queñi, Argentina

I visited this spot in Argentina in 2007; the wonderfully clear river had, along its rocky banks, some very cool carabids.  Four species were very common here:  a large, black, undescribed species of Bembidion (more on that later), a species of the Bembidion rufoplagiatum complex (possibly a mess of species that are hard to tell apart), and two species of the very curious genus Bembidarenas. All of these beetles live within 2 meters of the water, and some are abundant; in a couple hours of collecting I found about 150 of the undescribed Bembidion, and could have picked up many more.