Dichotomius (Dichotomius) mamillatus ( Felsche, 1901 )

9. Dichotomius (Dichotomius) mamillatus ( Felsche, 1901) View in CoL species group

Diagnosis: This species group was revised by Rossini and Vaz-de-Mello (2020). The species of the D. mamillatus species group is recognized by the following combination of characters: (1) Medium-sized to large-sized individuals (13–22 mm). (2) Head oval and twice as long as it is wide ( Fig. 17a, b View Figure 17 ). (3) Clypeus with two evident clypeal teeth, or inconspicous, surface with strong and well-defined transverse wrinkles ( Fig. 17a, b View Figure 17 ). (4) Ventral clypeal process conical with obtuse tip ( Fig. 17c View Figure 17 ). (5) Fronto-clypeal region of both sexes with a conical horn or with two small tubercles at middle with blunt or truncate ( Fig. 17a, b View Figure 17 ). (6) Protibial spur not angled or slightly angled near the apex ( Fig. 17d View Figure 17 ). (7) Pronotum either regularly convex (at most with two very weak and transversal concavities on the anterior side) or antero-medial region with a longitudinal depression and two distinct and obtuse humps on the superior side ( Fig. 17a, b View Figure 17 ). (8) Elytral striae bicarinate, shallow to distinctly impressed, with shallow to distinctly puntures in its extension. (9) Pygidium with complete or incomplete apical margin and evident punctures ( Fig. 17e View Figure 17 ). (10) Aedeagus with slender subgenital plate ( Fig. 17h View Figure 17 ). (11) Parameres subtriangular in lateral view ( Fig. 17f View Figure 17 ), without setae in the apical area ( Fig. 17 View Figure 17 f-h). (12) ME well sclerotized, large and asymmetrical ( Fig. 17l View Figure 17 ).

Composition: Four valid species: Dichotomius gandinii Rossini and Vaz-de-Mello, 2020 , D. mamillatus ( Felsche, 1901) , D. robustus ( Luederwaldt, 1935) and D. worontzowi ( Pereira, 1942b) .

Geographic distribution: Pacific Dominion (Sabana and Trinida Provinces), Boreal Brazilian dominion (all provinces), South Brazilian dominion (all provinces), Chacoan subregion Southeastern Amazonian dominion (Xingu-Tapajós province), Chacoan dominion (Cerrado province), and South American transition zone (Páramo province) ( Fig. 18a View Figure 18 ).