The oldest Bibio Geoffroy, 1762 (Diptera: Bibionidae) from the Paleocene of Menat (France)

Abstract

The lacustrine Konservat-Lagerstätte of Menat (Puy-de-Dôme, France) is a unique window in the terrestrial Paleocene environments of Western Europe (Wedmann et al., 2018). It has yielded an exceptional diversity of plants (leaves, flowers, seeds, pollen), and animals (vertebrates and arthropods, especially insects) (e.g., Piton, 1940). Nevertheless, flies are quite rare in this outcrop in which the paleo-entomofauna is dominated by beetles (69% of a collection of 3938 specimens). To date, this paleo-maar has given only one specimen of the family Bibionidae, a Plecia sp. (Nel, 2007). Piton (1940) also described a ‘Bibio sp.’, but Nel (2007) reexamined the two specimens of Piton, concluding that they are not bibionids. Thus, this family is clearly very rare in this outcrop. The Bibionidae seem to be quite rare in the Paleocene and early to middle Eocene outcrops of Western Europe (Oise amber, Baltic amber, Messel) (Gee et al., 2001; Nel, 2007; Skartveit & Wedmann, 2015; Skartveit, 2021). They are also rather rare in the late Eocene of the Isle of Wight (Krzemiński et al., 2019), while they are much more frequent in the younger, late Eocene, Oligocene, or Miocene paleolakes of France, Germany, and Spain (e.g., Monteils, Rott, Cereste, Dauphin, Aix-en-Provence, Rubielos de Mora, Ribesalbes, Montagne d’Andance, Sainte-Reine) (Peñalver-Molla, 1998, 2002; Skartveit & Nel, 2017; Skartveit & Wedmann, 2021). They are the most frequent insects in these outcrops.