Testing and optimizing metabarcoding of iDNA from dung beetles to sample mammals in the hyperdiverse Neotropics.

Over the past few years, insects have been used as samplers of vertebrate diversity by assessing the ingested-derived DNA (iDNA), and dung beetles have been shown to be a good mammal sampler given their broad feeding preference, wide distribution and easy sampling. Here, we tested and optimized the use of iDNA from dung beetles to assess the mammal community by evaluating if some biological and methodological aspects affect the use of dung beetles as mammal species samplers. We collected 403 dung beetles from 60 pitfall traps. iDNA from each dung beetle was sequenced by metabarcoding using two mini-barcodes (12SrRNA and 16SrRNA). We assessed whether dung beetles with different traits related to feeding, nesting and body size differed in the number of mammal species found in their iDNA. We also tested differences among four killing solutions in preserving the iDNA and compared the effectiveness of each mini barcode to recover mammals. We identified a total of 50 mammal OTUs (operational taxonomic unit), including terrestrial and arboreal species from 10 different orders. We found that at least one mammal-matching sequence was obtained from 70% of the dung beetle specimens. The number of mammal OTUs obtained did not vary with dung beetle traits as well as between the killing solutions. The 16SrRNA mini-barcode recovered a higher number of mammal OTUs than 12SrRNA, although both sets were partly non-overlapping. Thus, the complete mammal diversity may not be achieved by using only one of them. This study refines the methodology for routine assessment of tropical mammal communities via dung beetle 'samplers' and its universal applicability independently of the species traits of local beetle communities.

A revision of Dichotomius (Homocanthonides) Luederwaldt, 1929 (Coleoptera: Scarabaeidae: Scarabaeinae)

ABSTRACT The monospecific subgenus Dichotomius (Homocanthonides) is revised and its single species, Dichotomius (H.) smaragdinus (Perty, 1830) is redescribed and distinguished from other Dichotomius species. Dichotomius (H.) smaragdinus is a polymorphic species and its distribution comprises the Brazilian Cerrado. For the first time, morphological variation and male genital organ are described and illustrated. We believe that this species might be endangered due to extensive deforestation of Brazilian Cerrado by agricultural and pasture expansion. Thus, we highlight the importance of preserving this very unusual Dichotomius species.

Type specimens and names assigned to Coprophanaeus (Megaphanaeus) d'Olsoufieff, 1924, the largest New World dung beetles (Coleoptera: Scarabaeidae: Phanaeini).

Currently 13 species-group names assigned to the subgenus Megaphanaeus of Coprophanaeus are deemed available (or 'potentially available'), four of which denote valid species. In the present work we review the nomenclatural history of those names and conclude that two of them, Scarabaeus satelles Lichtenstein, 1796 and Copris ajax Sturm, 1826, are unavailable. For the other 11 names, we found type specimens of five, Scarabaeus bellicosus Olivier, 1789, Copris ensifer Germar, 1821, Phanaeus septentrionalis Pêssoa, 1934, P. vicinus Martínez, 1944, and P. vicinus var. argentinus Martínez, 1944. Two lectotypes are designated, one for Copris ensifer and other for Phanaeus septentrionalis. We were unable to locate the type series of the four names described by Castelnau (1840), i.e. Phanaeus ducalis, P. sylvanus, P. heros and P. miles, and of P. bonariensis Gory, 1844 and Scarabaeus lancifer Linné, 1767. For the latter, based on some iconotypes, we found that its type series was composite, including specimens of two different Megaphanaeus species, and, in addition, it was mixed with Copris ensifer type series. In order to fix the name to a sole species, a neotype is designated for Scarabaeus lancifer. The history of the names are presented in detail, and the application of these names to species is briefly re-discussed.

Taxonomic revision of the Dichotomius speciosus (Waterhouse, 1891) species group (Coleoptera: Scarabaeidae: Scarabaeinae).

The Dichotomius speciosus species group, endemic to the highlands of the Brazilian Atlantic Forest and included in the subgenus Luederwaldtinia is taxonomically revised. Dichotomius alvarengai new species and D. malyi new species are described. Dichotomius bucki is here considered to be a new synonym of D. opalescens, for which a lectotype is designated. The group, as well as its species, is diagnosed. A taxonomic key, illustrations and discussions on systematics and conservation of the group are provided.