Research Article |
Corresponding author: Francisco Tello ( ftelloa@yahoo.cl ) Academic editor: Andrey Frolov
© 2021 Francisco Tello, José R. Verdú, Michele Rossini, Mario Zunino.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Tello F, Verdú JR, Rossini M, Zunino M (2021) Onthophagus pilauco sp. nov. (Coleoptera, Scarabaeidae): evidence of beetle extinction in the Pleistocene–Holocene transition in Chilean Northern Patagonia. ZooKeys 1043: 133-145. https://doi.org/10.3897/zookeys.1043.61706
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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 pilauco sp. 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 pilauco sp. 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. pilauco sp. 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.
Dung beetle, extinction, fossil beetles, new species, Pleistocene, South America
The South American Pleistocene–Holocene transition (~16.0–11.0 k cal yr BP) has been characterized by drastic changes in climatic conditions, animal and plant diversity, and types of early-human occupation (
In addition, the extinction of megafauna caused drastic changes in forest ecosystems, as these animals (e.g., the Gomphotheriidae) were fundamental in the past to support a series of important trophic relations (
In South America, most of the evidence of the extinction of dung beetle fauna is based on fossil breeding balls (i.e., ichnospecies) in the early, middle and late Pleistocene (
In this study, we analyzed fossil remains from a late Pleistocene sequence collected at the paleoarcheological site Pilauco in Chilean Northern Patagonia. The fossil remains are tentatively classified in the Onthophagus osculatii species-complex (Coleoptera: Scarabaeidae: Scarabaeinae) (
The main goals of this study were to analyze the morphology of the fossil remains, to discuss the paleoecological implications and biogeographical distributions of the extant Chilean dung beetle fauna, with emphasis on South American Onthophagus, and to suggest a taxonomic placement for these fossil remains.
The Pilauco archeological and paleontological site is located in the city of Osorno, Chilean Northern Patagonia (40°34'S, 73°07'W) (Fig.
Stratigraphically, the Pilauco site is composed of four principal beds (Fig.
Pollen records have recently indicated that the environment associated with bed PB-7 contained mainly non-arboreal taxa, such as Poaceae, Asteraceae, Solanaceae, and an aquatic flora (
CEMT Seção de Entomologia da Coleção Zoológica, Universidade Federal de Mato, Grosso, Cuiabá, Brazil;
MPDO Museo Pleistocénico de Osorno, Osorno, Chile;
MZ Mario Zunino private collection, Asti, Italy;
The fossil beetle remains were recovered from the sediment using an adaptation of the water flotation technique described by Hoganson et al. (1989) (see also
Suborder Polyphaga Emery, 1886
Family Scarabaeidae Latreille, 1802
Holotype. Male, minor form. Clypeus sub-trapezoidal and slightly elongated forward, with anterior margin narrowly and slightly reflexed, head margin barely sinuated at the clypeo-genal junction. Fronto-clypeal region without carina, frons with two close, weak tubercles, strongly advanced in position, in line with the anterior margin of the eyes (Fig.
Female unknown.
Onthophagus pilauco sp. nov. is considered to be a close relative of O. confusus Boucomont, 1932 and O. insularis Boheman, 1858, as it shares the following morphological characters with these species: sub-trapezoidal shape of the clypeus; small, slightly deeper cephalic punctation, coupled with very shallow wrinkles in proximity to the genal and clypeal margins. Although the fronto-clypeal region is significantly damaged, there is no indication of a possible carina.
The Pilauco dung beetle (EN) and estercolero de Pilauco (ES).
The name of the new species refers to the archeopaleontological site from which the fossil remains were collected.
From our observations, the fossil remains found at Pilauco correspond to a new and extinct species of the genus Onthophagus, closely related to the hircus group. Onthophagus pilauco sp. nov. represents the first record of an endemic species of this genus in Chile. Moreover, this record brings new evidence of beetle extinction related to the Pleistocene–Holocene transition and massive defaunation after a possible cosmic impact and/or YD cooling reversal events.
Despite the beetle remains only being represented by cephalic parts (clypeus, right gena and frons; fronto-clypeal region partly damaged; left gena absent; see Fig.
Comprehensive knowledge of the Chilean beetle fauna suggests that only a few species (nine) can be considered to be exclusively associated with dung resources (
The Deltochilini group is distributed in the pantropical zone, being especially diversified in the northern areas of South America. The genus Tesserodoniella is related to the Australian genera Tesserodon and Aptenocanthon and their ancestors probably originated from the Gondwana supercontinent (
On the other hand, the extinction of large animals in South American Pleistocene environments has invoked multiple climate- and human-activity-related hypotheses, and interactions between them (
We would like to thank to Dr Mario Pino for his collaboration in the manuscript revision, and Mario Elgueta for the primary approximation to the taxonomical identities. We are grateful to Fernanda Torres for the creation of the Figure