Ambush predator guild of Backswimmers in the Cretaceous of Argentina

PETRULEVICIUS, J. F, SALLENAVE, S. Y NEL, A.

Pretoria

Congreso; III International Congress on Palaeoentomology, II International Meeting on Paleoarthropodology y III International Congress on amber; 2005

South African National Biodiversity Institute

Notonectidae are rather frequent in the Cenozoic and their Mesozoic record is much more incomplete, with several taxa of uncertain affinities. The present discovery of at least two species of Notonectidae belonging to the modern subfamilies Notonectinae and Anisopinae in the Aptian-earliest Albian of west-central Argentina is of great interest for the knowledge of this family. The specimens of Notonectinae belong to a new species of the recent genus Notonecta. The specimens of Anisopinae seem to belong to a new genus and species. Specimens are considered to be exuviae. Exuviae of both species are represented by different instars and preserved in the same strata. Bodies are exceptionally preserved, at least in the prospected position of the lake. Recent species of Notonecta could also live together with Anisopinae, exhibiting asymmetrical intraguild predation. They could live in the same space, in lentic - static water systems, but heterogeneity of environment can promote the coexistence of conflicting species. It is noteworthy that notonectids from La Cantera, 120 Ma ago, formed a guild homologous to the recent Notonectinae-Anisopinae ambush predator guild in freshwater environments and it is likely that also presented IGP interaction.