Onthophagus pilauco sp. nov. (Coleoptera, Scarabaeidae): evidence of beetle extinction in the Pleistocene–Holocene transition in Chilean Northern Patagonia

Abstract

The South American Pleistocene–Holocene transition has been characterized by drastic climatic and diversity changes. These rapid changes induced one of the largest and most recent extinctions in the megafauna at the continental scale. However, examples of the extinction of small animals (e.g., insects) are scarce, and the underlying causes of the extinction have been little studied. In this work, a new extinct dung beetle species is described from a late Pleistocene sequence (~15.2 k cal yr BP) at the paleoarcheological site Pilauco, Chilean Northern Patagonia. Based on morphological characters, this fossil is considered to belong to the genus Onthophagus Latreille, 1802 and named Onthophagus pilaucosp. nov. We carried out a comprehensive revision of related groups, and we analyzed the possible mechanism of diversification and extinction of this new species. We hypothesize that Onthophagus pilaucosp. nov. diversified as a member of the osculatii species-complex following migration processes related to the Great American Biotic Interchange (~3 Ma). The extinction of O. pilaucosp. nov. may be related to massive defaunation and climatic changes recorded in the Plesitocene-Holocene transition (12.8 k cal yr BP). This finding is the first record of this genus in Chile, and provides new evidence to support the collateral-extinction hypothesis related to the defaunation.

A new extinct species of Scybalophagus dung beetle supports the collateral extinction hypothesis at the Chilean South American Pleistocene–Holocene boundary

“…Moreover, the presence of megaherbivores was a critical factor for the distribution of dung beetles during the LGM in South America (Tello et al, 2017(Tello et al, , 2021b. As these megaherbivores provided dung sources for these commensal organisms, they also modified the environment, providing open-pasture habitats (Barnosky et al, 2016;González-Guarda et al, 2017).…”

“…This is also supported by the extinct Onthophagus pilauco, recorded in the same deposit. Thus, in the case of megaherbivore-dependent species such as dung beetles, the collateral extinction hypothesis provides a parsimonious explanation for the extinction of this fauna (Zinovyev, 2011;Tello et al, 2021aTello et al, , 2021b.…”

“…The extinction of megaherbivores caused a cascade of effects on multiple trophic levels (Owen-Smith, 1987;Galetti et al, 2018), such as plant distribution changes (Barnosky et al, 2016;González-Guarda et al, 2017), nematode extinction (Beltrame et al, 2017(Beltrame et al, , 2020, and beetle distribution changes and/or extinctions (Hoganson and Ashworth, 1992;Ashworth, 2007;Zunino, 2013;Tello et al, 2021b). For instance, collateral species turnover has been reported in the paleofauna of the Northern Hemisphere, where megaherbivores (i.e.…”

“…Thus, the groups that went extinct or suffered distributional changes as a consequence of large mammal extinctions are also called ‘mammoth fauna/biota’. Endoparasitic mammoth‐nematodes went extinct due to their strict dependence upon large mammals (Beltrame et al, 2020), while for dung beetles, the extinction may have been driven by the reduction of dung sources/mammal loss (Zinovyev, 2011; Schweiger and Svenning, 2018; Tello et al, 2021b), but also by climatic changes during successive glacial contractions/expansions during the Pleistocene (Nolasco‐Soto et al, 2017). However, evidence of the impacts of megafaunal extinction on these animals has been deduced via their fossil traces (Sánchez et al, 2013), but fossils or pseudo‐fossilized body parts are scarce (Zunino, 2013; Tarasov et al, 2016; Tello et al, 2021b).…”

“…Endoparasitic mammoth‐nematodes went extinct due to their strict dependence upon large mammals (Beltrame et al, 2020), while for dung beetles, the extinction may have been driven by the reduction of dung sources/mammal loss (Zinovyev, 2011; Schweiger and Svenning, 2018; Tello et al, 2021b), but also by climatic changes during successive glacial contractions/expansions during the Pleistocene (Nolasco‐Soto et al, 2017). However, evidence of the impacts of megafaunal extinction on these animals has been deduced via their fossil traces (Sánchez et al, 2013), but fossils or pseudo‐fossilized body parts are scarce (Zunino, 2013; Tarasov et al, 2016; Tello et al, 2021b). Moreover, the mechanisms that regulated the collateral extinctions of the South American paleofauna remain underexplored, and few examples have been reported in the specialized literature (Tarasov et al, 2016; Galetti et al, 2018).…”