Scarabaeine dung beetles are the dominant dung feeding group of insects and are widely used as model organisms in conservation, ecology and developmental biology. Due to the conflicts among 13 recently published phylogenies dealing with the higher-level relationships of dung beetles, the phylogeny of this lineage remains largely unresolved. In this study, we conduct rigorous phylogenetic analyses of dung beetles, based on an unprecedented taxon sample (110 taxa) and detailed investigation of morphology (205 characters). We provide the description of morphology and thoroughly illustrate the used characters. Along with parsimony, traditionally used in the analysis of morphological data, we also apply the Bayesian method with a novel approach that uses anatomy ontology for matrix partitioning. This approach allows for heterogeneity in evolutionary rates among characters from different anatomical regions. Anatomy ontology generates a number of parameter-partition schemes which we compare using Bayes factor. We also test the effect of inclusion of autapomorphies in the morphological analysis, which hitherto has not been examined. Generally, schemes with more parameters were favored in the Bayesian comparison suggesting that characters located on different body regions evolve at different rates and that partitioning of the data matrix using anatomy ontology is reasonable; however, trees from the parsimony and all the Bayesian analyses were quite consistent. The hypothesized phylogeny reveals many novel clades and provides additional support for some clades recovered in previous analyses. Our results provide a solid basis for a new classification of dung beetles, in which the taxonomic limits of the tribes Dichotomiini, Deltochilini and Coprini are restricted and many new tribes must be described. Based on the consistency of the phylogeny with biogeography, we speculate that dung beetles may have originated in the Mesozoic contrary to the traditional view pointing to a Cenozoic origin.
The species of the genus Ontherus, endemic to Latin America, are revised. A key in English and Spanish for the identification of adults of the 58 recognized species is provided. Three subgenera are recognized (Caelontherus nov., Planontherus nov. and Ontherus s.str.). The following 29 species are described as new: O. hadros, O. magnus, O. gilli, O. ashei, O. politus, O. sanctaemartae, O. tenuistriatus, O. obliquus, O. howdeni, O. diabolicus, O. pilatus, O. sextuberculatus, O. lunicollis, O. monilistriatus, O. pseudodidymus, O. rectus, O. pubens, O. ulcopygus, O. cambeforti, O. raptor, O. planus, O. edentulus, O. rectangulidens, O. lobifrons, O. androgynus, O. amplector, O. atlantidis, O. insolitus, O. stridulator. The following new synonymies are proposed (the first specific name being valid): O. kirschii Harold = O. elongatus Waterhouse; O. alexis (Blanchard) = O. didymus Erichson = O. glaucinus Erichson = O. nevinsoni Waterhouse; O. incisus (Kirsch) = O. thoracicus Waterhouse; O. azteca Harold = O. villosus Luederwaldt = O. strius Howden and Young; O. cephalotes Harold = O. quadrituberculatus Luederwaldt. The variety O. zikani var. carinicollis Luederwaldt is now recognized as a valid species. Species are arranged into groups according to their phylogenetic relationship, with a brief diagnosis given for each of the 11 groups of species. The following information is given for each species, when appropriate: detailed literature review, synonymy, description or redescription, illustration of important morphological characters, data of material studied, and geographic distribution.
The dung beetle subfamily Scarabaeinae is a cosmopolitan group of insects that feed primarily on dung. We describe the first case of an obligate predatory dung beetle and contrast its behaviour and morphology with those of its coprophagous sympatric congeners. Deltochilum valgum Burmeister killed and consumed millipedes in lowland rainforest in Peru. Ancestral ball-rolling behaviour shared by other canthonine species is abandoned, and the head, hind tibiae and pygidium of D. valgum are modified for novel functions during millipede predation. Millipedes were killed by disarticulation, often through decapitation, using the clypeus as a lever. Beetles killed millipedes much larger than themselves. In pitfall traps, D. valgum was attracted exclusively to millipedes, and preferred injured over uninjured millipedes. Morphological similarities placing D. valgum in the same subgenus with nonpredatory dung-feeding species suggest a major and potentially rapid behavioural shift from coprophagy to predation. Ecological transitions enabling the exploitation of dramatically atypical niches, which may be more likely to occur when competition is intense, may help explain the evolution of novel ecological guilds and the diversification of exceptionally species-rich groups such as insects.
The taxonomy of the genera Deltorhinum Bates and Lobidion gen. nov. is reviewed. A genus and seven species are described as new (Lobidion gen. nov., Deltorhinum armatum sp. nov., D. bilobatum sp. nov., D. guyanensis sp. nov., D. kempffmercadoi sp. nov., D. robustum sp. nov., D. vazdemelloi sp. nov., Lobidion punctatissimum sp. nov.). Illustrations of diagnostic characters and an identification key are provided.
The taxonomy and systematics of the genus Digitonthophagus Balthasar (Coleoptera: Scarabaeidae: Scarabaeinae: Onthophagini) is revised. A detailed study of the male genitalia combined with external morphology suggests that the variability, previously recognized, for D. gazella is hiding a species complex within the Afrotropical region and the Arabian Peninsula. The current study recognizes 16 species; 13 from the Afrotropical region and Arabian Peninsula and three from the eastern portion of the Saharo-Arabian region and the continental Indomalayan region. Species are organized into six species groups based on the results of the morphology-based phylogenetic analysis. The following 12 species are described as new: D. aksumensis Génier new species; D. biflagellatus Génier new species; D. dilatatus Génier new species; D. eucatta Génier new species; D. falciger Génier new species; D. fimator Génier new species; D. namaquensis Génier new species; D. petilus Génier new species; D. sahelicus Moretto new species; D. uks Génier new species; D. ulcerosus Génier new species; and D. viridicollis Génier new species. In order to stabilize nomenclature, lectotypes are designated for Scarabaeus bonasus Fabricius, 1775; Scarabaeus catta Fabricius, 1787, and Onthophagus gazella lusinganus d’Orbigny. A neotype is designated for Scarabaeus dorcas Olivier, 1789 whose status and synonymy need to be altered in order to clarify the status of Scarabaeus gazella auctorum, the widely introduced species with economic importance. A naming scheme is presented for the sclerites of the internal sac. External and male genitalia are illustrated and distribution maps are provided for each species.
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