Studies of the mesovoid shallow substratum can change the accepted autecology of species: the case of ground beetles (Coleoptera, Carabidae) in the Sierra de Guadarrama National Park (Spain)

Abstract

The family Carabidae is of particular interest not only due to its great specific diversity but also due to the geophilic nature of many of its members, which makes them good bioindicators of soil characteristics. The diversity of the epigean Carabidae is relatively well studied. However, there are no robust data on the presence of these beetles in hypogean habitats of non–karstic substrate and, therefore, without the development of caves. In the present study, we sampled the mesovoid shallow substratum (MSS) at various sites in the Sierra de Guadarrama National Park, with the aim of characterising the Carabidae hypogean fauna. Among many other organisms, we collected 12 species of Carabidae. Of these, despite being known from epigean/edaphic habitats, Leistus (Leistus) constrictus Schaufuss, 1862, Nebria (Nebria) vuillefroyi Chaudoir, 1866, Trechus (Trechus) schaufussi pandellei Putzeys, 1870, and Laemostenus (Eucryptotrichus) pinicola (Graells, 1851) are consistently reported from MSS habitats, albeit with certain differences as regards their occupation of subterranean spaces. The species from forest–dwelling (thermophilous) lineages, T. (T.) schaufussi pandellei and L. (E.) pinicola, presented a higher prevalence in subsoil cavities at lower altitudes, whereas those from orobiont (psychrophilic) lineages, L. (L.) constrictus and N. (N.) vuillefroyi, predominated in subsoils at higher altitudes. As regards the presence of these four species during their different life cycle stages, we found that N. (N.) vuillefroyi was present and abundant as both larval (in the three preimaginal stages) and imago stages, showing the most evident trend towards an hypogean lifestyle. In contrast, for the other three species, only one of the two stages showed a high presence on hypogean habitats. The facultative hypogean capabilities of N. (N.) vuillefroyi and L. (L.) constrictus calls into question the protected status conferred on both species when it was thought that they were exclusively epigean.