Abstract
Abstract Within the subgenus Dichotomius (Selenocopris) Burmeister 1846, D. nisus (Olivier, 1789) and D. superbus (Felsche, 1901) had been historically arranged in the “Nisus” section by Luederwaldt, however, according to the revised classification of the subgenus, the two species now belong to different species groups. In this paper, the taxonomic history concerning the species once included by Luederwaldt in the “Nisus” section is revised and discussed. The following new synonyms are proposed: Pinotus taunayi (Luederwaldt, 1931) as a subjective synonym of D. geminatus (Arrow, 1913), and Pinotus taunayi pilosus (Luederwaldt, 1931) as a subjective synonym of D. nisus. Lectotypes are designated for D. nisus and Pinotus garbei. Redescriptions, diagnoses and updated distribution data are provided for D. nisus and D. superbus. The diagnostic characters of the male genitalia of these species are described and illustrated for the first time.
Highlights
The genus Dichotomius Hope, 1838 is endemic to the Western Hemisphere and widely distributed in the American continent, with the occurrence of species from the United States to Argentina (Nunes and Vaz-de-Mello, 2013)
We are aware that D. nisus is a very common species and other specimens of D. superbus are present in other collections, our aim is to present a synopsis, and we do not intent to detail the completeness of their geographical distributions, no specimens have been examined by us in other collections that came from localities far from the general distributions shown here
We propose that Pinotus taunayi is a new subjective synonym of D. geminatus (Arrow, 1913), while Pinotus taunay ipilosus is a new synonym of D. nisus
Summary
The genus Dichotomius Hope, 1838 is endemic to the Western Hemisphere and widely distributed in the American continent, with the occurrence of species from the United States to Argentina (Nunes and Vaz-de-Mello, 2013). It currently harbors around 200 valid species, of which about 150 are found in South America (Nunes and Vaz-de-Mello, 2019). Dichotomius is one of the most diverse genera of Neotropical dung beetles These medium-sized to large beetles occurs mainly in forests, but Dichotomius species can be found in dry habitats and pastures (Tissiani et al, 2017). Species belonging to D. (Selenocopris) are distinguished from other Dichotomius by the following combination of characters: 1) two clypeal teeth separated by a central emargation; 2) rounded head margin with no angulation at the clypeogenal junction (except for some species that exhibit a tooth at this junction); 3) metasternal pilosity, in general, abundant at the lateral lobes and 4) the sixth abdominal ventrite of females not extending beyond the apex of the pygidium nor with a pair of central tubercles (Luederwaldt, 1929; Vaz-de-Mello et al, 2011; Nunes and Vaz-de-Mello, 2019)
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