First fossil assemblage of darkling beetles (Coleoptera: Tenebrionidae) from Buenos Aires, Argentina: evidence of dry climate during the late Pleistocene in the humid Pampas

Late Pleistocene outcrops exposed in Buenos Aires province, Argentina, represent one of the most informative sources for paleoecological studies on South American fauna and flora. Several proxies have been used for studying Pleistocene environmental conditions in the Pampas, but only a few were based on paleoentomological data. The aims of this study are to present the first record of three species of darkling beetles from the late Pleistocene of Buenos Aires province and to provide new paleoenvironmental information. The sediments containing fossil insects correspond to the Guerrero Member of the Luján Formation and were dated between 12,100 ± 100 14C BP and 13,400 ± 200 14C BP. Specimens of Nyctelia picipes (Billberg), Epipedonota cristallisata Waterhouse and Scotobius pilularius Germar were identified. To provide information about past climate, the particular climate requirements of these species were analyzed by using the Mutual Climatic Range method. This association could indicate the first pulse of post-glacial climate recovery and the replacement by the insect fauna currently inhabiting the area. This study is one of the first approaches to the Quaternary paleoentomology of Argentina, and highlights the potential of paleoentomological information, when evaluated in combination with previous knowledge on global climate conditions after the last glacial maximum.