Taxonomic revision of Dichotomius (Cephagonus) Luederwaldt 1929 and the taxonomic status of remaining Dichotomius Hope 1838 subgenera (Coleoptera: Scarabaeidae: Scarabaeinae: Dichotomiini)
Dichotomius nomenclature is revised under the light of comparisons between type material and large series vouchered in several museums. Its division into four subgenera is redefined as follows: Dichotomius s. str., Selenocopris Burmeister, revised status, Cephagonus Luederwaldt revised status and Homocanthonides Luederwaldt. The species formerly in the subgenus Selenocopris (sensu Martínez 1951), except for those belonging to the D. bicuspis species-group, are transferred to Cephagonus, of which Pinotus fissus Harold is designated as type-species. Cephagonus has now 40 species: 38 spp. in five species groups: 1) D. ascanius species-group (includes D. ascanius (Harold), D. mundus (Harold) and D. socius (Luederwaldt)); 2) D. fissus species-group (includes D. fissus (Harold), D. fonsecae (Luederwaldt), D. baiano n. sp., D. fernadosilvai n. sp., D. filgueirasi n. sp. and D. seag n. sp.; 3) D. quadraticeps species-group (includes D. quadraticeps (Felsche), D. semicircularis (Luederwaldt) D. aielloae Nunes, D. clypeatus (Luederwaldt) and the cryptic species D. fissiceps (Felsche), D. reichei (Harold), arnaudi n. sp., D. asenjoi n. sp., D. barbarae n. sp., D. blancoi n. sp., D. candango n. sp., D. edmondsi n. sp., D. frizzasae n. sp., D. gardneri n. sp., D. feeri n.sp., D. furtadoi n. sp., D. emas n. sp., D. marcoscarvalhoi n. sp., D. paschoali n. sp., D. ricardosilvai n. sp., D. tissianiae n. sp.; 4) D. ingens species-group (includes the brachypterous species D. ingens (Luederwaldt), D. darwini Nunes & Vaz-de-Mello, D. manni Nunes & Vaz-de-Mello, D. paresi Nunes & Vaz-de-Mello and D. periotoi Nunes & Vaz-de-Mello) and 5) D. spadiceus species-group (includes D. spadiceus (Luederwaldt), D. itatiaiaensis n. sp. and D. lucianomourai n. sp.). Two new species, D. rondoniaensis n. sp. and D. vargasae n. sp. are described but not assigned to any species-groups. Lectotypes are designated for Pinotus ascanius piceus Luederwaldt (n. syn. of D. bicuspis), Pinotus ascanius Harold, Pinotus ascanius pygidialis Luederwaldt (n. syn. of D. ascanius), Pinotus mundus Harold, Pinotus simulans Luederwaldt (n. syn. of D. mundus), Pinotus socius Luederwaldt, Pinotus fissus Harold, Pinotus transiens Luederwaldt (n. syn. of D. reichei Harold), Pinotus fissiceps Felsche, Pinotus acutircornus Luederwaldt (n. syn. of D. spadiceus). Diagnoses, new species descriptions, identification key, illustrations and geographical data are provided for all Cephagonus species.
