Aphengium Harold, 1868

Aphengium Harold 1868: 82 (original description); Harold 1869: 1001 (catalogue); Bates 1887: 42 (taxonomic comments); Waterhouse 1890: 379 (taxonomic comments); Gillet 1911: 49 (catalogue); Blackwelder 1944: 203 (checklist); Cook 1998: 631 (taxonomic comments); Vaz-de-Mello 2000: 186, 190 (checklist); Vaz-de-Mello 2008: 12, 13 (systematic position); Vaz-de-Mello et al. 2011: 4, 13, 21, 28, 36, 43, 49 (identification keys).

Type species. Aphengium sordidum Harold, by monotypy

Diagnosis. Pronotum (especially at sides) and elytra densely pilose, with long setae. Last abdominal sternite expanded and crowding out other sternites along midline; other sternites visible only laterally (Fig. 3). Hypomera deeply excavated anteriorly (Fig. 1). Profemur lacking trochantofemoral anterior pit. These characters distinguish Aphengium from all other New World Scarabaeinae genera.

Description. Body. Oval to elongate-oval (viewed dorsally). Dorsal surface with foveiform punctures and dense setae. Colour. Black or reddish brown, matte or with silky sheen. Length. Small (6–10 mm). Head. Clypeus bidentate; clypeal teeth separated by either a narrow or broad emargination (Figs. 9–10). Medial part of clypeal surface concave. Margin between clypeal teeth and clypeogenal suture almost straight. Margin of gena strongly curved outward, with a groove along its margin. Clypeogenal suture distinct. Frontoclypeal carina inconspicuous. Eyes comma-shaped in dorsal view; interocular width at least 12 times the eye width (Figs. 15– 16). Pronotum. Convex. Foveiform punctures variable according to species, dense or sparse. Punctures larger and closer on lateral and posterior portions of pronotum. Lateral pronotal impressions with a small rounded tubercle, poorly differentiated from surrounding surface. Posteromedian pronotal fossae absent. Elytra. Lateral margins slightly curved outwards. Elytral striae narrow, carinate margins close and almost contiguous. Interstriae flattened, with foveiform punctures surrounded by microgranulation. Pseudepipleural carina complete, visible for entire length of epipleuron. Abdomen. Pygidium almost horizontal and rounded at apex (Figs. 3–4), completely emarginated, visible in ventral view; emargination bounded internally by a groove. Legs. Profemur lacking trochantofemoral anterior pit. Meso and metafemur emarginated along its anterior margin. Protibia subtriangular, flat, with three external teeth; apical internal angle straight; margin of apical tooth continuous (not forming angle) with apical truncation. External margin of protibia lacking denticles between its base and the basal tooth. Meso and metatibia strongly widened at apex, subtriangular (Fig. 2). Length of basal metatarsomere subequal to that of following two tarsomeres combined (Fig. 2). Secondary sexual characters. Female clypeal teeth more triangular, longer and more acute (Figs. 10, 16, 22, 28) than those of males (Figs. 9, 15, 21, 27). Protibial spur spiniform and conical in females (Fig. 6). Male protibial spur wider, spatuliform (Fig. 5). Anterior angle of pronotum more acute in females (Figs. 12, 18, 30). Differences between the sexes in the head and pronotum punctures vary according to species. Aedeagus. Parameres symmetrical, short or elongate, simple, without ornamentation or setae (Figs. 31–34). Superior right peripheral sclerite (SRP) sigmoid (Figs. 35–36). Fronto-lateral peripheral sclerite (FLP) with irregular shape (Figs. 37–40).

Geographical distribution. Species of Aphengium inhabit wet forests, particularly at lower altitudes and mainly in coastal parts of the Brazilian Atlantic rainforest. However, each species appears to be distributed within one defined region of Atlantic rainforest, with three distribution gaps between them (Fig. 41). The northern gap includes the coastal region located between the São Francisco river and the Todos os Santos bay, separating A. ibateguara sp. nov. and A. curtum sp. nov .. The central gap includes the area between the mouths of the Pardo and Mucuri rivers, separating A. curtum sp. nov. and A. cupreum. The southern gap includes the region between the Paraíba do Sul river and Guanabara bay, separating A. cupreum and A. sordidum.

So far, extensive sampling in some lower elevation parts of the Atlantic forest located within these gaps have not produced Aphengium. We examined dung beetles from Sapiranga forest reserve in the first gap. In the second gap numerous field trips have been made to Porto Seguro and neighboring areas. Finally, in the third gap there are historical collections of dung beetles from the São Fidélis region but no recent extensive collecting in lower altitude forest fragments.