The most ancient Platyperlidae (Insecta, Plecoptera) from early Late Triassic deposits in southern South America

GALLEGO, O.F.; RÉBORI, L.O.; ZAVATTIERI, A.M.; SINITSHENKOVA, N.; LARA, M.B.; MARTINS-NETO, R.G.

AMEGHINIANA

ASOCIACION PALEONTOLOGICA ARGENTINA

Lugar: Buenos Aires; Año: 2010

0002-7014

The new insect specimen Platyperla marquati sp. nov. described herein is a nymphal stage and belongs to the Order Perlida (= Plecoptera) Latreille (stoneflies). It comes from the uppermost section of the Potrerillos Formation, which crops out in the south of the cerro Cacheuta, at the southern extremity of the Precordillera (Mendoza Province, Argentina). The early Late Triassic Potrerillos/Cacheuta sedimentary succession in this area includes fluvial, deltaic and lacustrine facies that reflect deposition in a border of the Cacheuta depocenter of the Cuyana Basin. This is the second complete insect and the first autochthonous aquatic insect from Triassic beds in Argentina, and also the first record of the family Platyperlidae in Gondwana. This finding demonstrates the similarity of aquatic insect faunas in Mesozoic deposits all over the world, at least of the morpho-ecological types of the aquatic stages. In Triassic times the lacustrine insect fauna started to evolve; it became diverse during the Jurassic and Early Cretaceous. Detailed geological studies have led to the recognition that equivalents levels to the Middle Triassic lower units of the Uspallata Group (Río Mendoza and Cerro de Las Cabras formations) crop out on the south-eastern flank of the cerro Cacheuta. Therefore, a new geological map and interpretation for this area are also presented.