Abstract

Nine rainpools in the savanna of northern Bolivia were examined using a random, semi‐quantitative sampling method. Both the macrophyte and insect assemblages showed that the longevity of a pool tended to be the dominant influence on the colonizing biota in the Tropics. Twenty‐four families of insects were recorded, including seven Heteroptera, five Odonata and five Diptera. The highly ephemeral (A‐)pools, which were dominated by beetles, differed from longer‐lived waters (B‐ and C‐pools). The composition of the insect assemblages in the B‐ and C‐pools formed a continuum, and the Chironomidae became more numerous and diverse with increasing water body longevity and habitat complexity. Out of the 20 recorded chironomid genera, three uncommon larval types are presented (Chironomini Gen X, "Tanytarsus”; (b), "Tanytarsus”; (dark L.o.). The study area is among the least researched in Bolivia, so many insects, and the chironomids in particular, are suspected as being newly discovered species.