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.

RESUMO Espécies de rola-bostas foram coletadas entre maio de 2016 e julho de 2017 com armadilhas de queda iscadas com fezes humanas em quatro localidades de Mata Atlântica com diferentes níveis de perturbação no estado do Rio Grande do Sul, sul do Brasil. Foram amostrados 5.535 indivíduos pertencentes a 46 espécies. Canthidium aff. trinodosum (20,71%), Eurysternus parallelus Castelnau, 1840 (14,82%), Onthophagus catharinensis Paulian, 1936 (12,09%), Scybalocanthon nigriceps (Harold, 1868) (7,61%), Eurysternus caribaeus (Herbst, 1789) (7,49%) e Canthon rutilans cyanescens Harold, 1868 (7,22%) foram as espécies mais abundantes, que representaram 70% dos indivíduos amostrados. A Reserva Biológica Moreno Fortes teve a maior riqueza e o Morro do Cerrito a maior abundância, enquanto Val Feltrina apresentou os menores valores. A maior similaridade ocorreu entre o Parque Estadual do Turvo e a Reserva Biológica Moreno Fortes, enquanto a Reserva Biológica Moreno Fortes e a Val Feltrina tiveram a menor similaridade. Apenas 11 espécies (23,9%) ocorreram em todos os locais, enquanto 14 espécies foram restritas a apenas um dos fragmentos. Tanto a riqueza como a abundância de Scarabaeinae foram positivamente correlacionadas com a temperatura do local, mas não com a precipitação.

ABSTRACT Dung beetle species were collected between May 2016 and July 2017 with pitfall traps baited with human feces in four Atlantic Forest sites with different levels of disturbance in the state of Rio Grande do Sul, southern Brazil. We sampled 5,535 individuals belonging to 46 species. Canthidium aff. trinodosum (20.71%), Eurysternus parallelus Castelnau, 1840 (14.82%), Onthophagus catharinensis Paulian, 1936 (12.09%), Scybalocanthon nigriceps (Harold, 1868) (7.61 %), Eurysternus caribaeus (Herbst, 1789) (7.49%), and Canthon rutilans cyanescens Harold, 1868 (7.22%) were the most abundant species, which represented 70% of the individuals sampled. Moreno Fortes Biological Reserve had the higher richness and Morro do Cerrito the higher abundance, while Val Feltrina presented the lowest values. The greatest similarity occurred between Turvo State Park and Moreno Fortes Biological Reserve, while Moreno Fortes Biological Reserve and Val Feltrina had the lowest similarity. Only 11 species (23.9%) occurred in all sites, while 14 species were restricted to only one of the fragments. Both abundance and richness of dung beetles were positively correlated with site temperature but not with precipitation.