Bothynus tricornis Arrow, 1937

(Figs. 3 A–E; 8C; 9C; 10C; 11C;12C)

Bothynus tricornis Arrow 1937: 45 (original description).

Diagnosis. Bothynus tricornis is distinguished from other species of the group by the following combination of characters: major and median males with three remarkable pronotal horns (Fig. 3 A–B); three tubercles instead horns in minors (Fig. 3C); pronotal concavity extremely deep (Fig. 3 A– C); hypomeron emarginate in ventral view (Fig. 3E); parameres with rounded basal half and apical half with lateral flaps gradually expanded toward apex (Fig. 8C); female differs from other females of group by the pronotal concavity densely covered by coalescent punctures (Fig. 10C); tergite VIII with apical invagination strongly emarginate and transverse about 7.9 times wider than long (Fig. 11C).

Type material. Holotype male, Bothynus tricornis Arrow, 1937: examined (NHM). Labeled: “ Brazil: Sabara- Bello [Sabará-Belo] Horizonte, Rio das Velhao [Velhas], A.G.N.Chalmers, B.M. 1932-II. ”

Additional material examined. 6 males and 3 females. Brasil: Minas Gerais: Mirandópolis, Taiobeiras, XI.2014, R. Koike— 4♂ 2♀ (CERPE); Perdões, 12.X.2006, F. Campos— 1♂ (EPGC); Passos, 24.X.1963 C. Elias— 1♀ (DZUP). Rio de Janeiro: Teresópolis, no date, P. Schirch— 1♂ (MNRJ) .

Redescription. Male. Body length: 25.0– 30.1 mm. Body width: 11.0–13.0 mm. Color: Completely dark (Fig. 3 A–C). Head: Clypeus subpentagonal, moderately arched at middle, surface densely rugopunctate, with scarce setae on sides, apical half strongly constricted laterally, basal half with subparallel raised sides. Frontoclypeal suture with 2 strong, slender tubercles. Interocular width equals 2.4 transverse eye diameters; frontal surface densely rugopunctate, setose on sides. Eye canthus subtriangular. Mouthparts: Mandibles bidentate, teeth conic, strong. Maxilla with quadridentate galea; 1 strong tooth at apex, apical, 3 moderate teeth at base. Pronotum: Horned, with 3 remarkable upcurved horns (1 horn on each side, 1 horn on apex); concavity strongly deep, broad, occupying about ½ of pronotal area. Major males with bifurcated horns; apical horn exceeding the head length, covering it partially in dorsal view (Fig. 3A). Median males with weak apical bifurcation; apical horn not exceeding the head length (Fig. 3B). Minor males with pronotal tubercles instead of horns (Fig. 3C). Pronotal surface finely punctate, with few setae scattered on anterior area; anterior angles strongly constricted in frontal view. Scutellar shield: From parabolic to subtriangular. Elytra: Nearly completely smooth, striae barely marked, punctures only observed under 90X magnification. Venter: Hypomeron strongly emarginate in ventral view (Fig. 3E). Legs: Metatibia with spatulate internal spur. Abdomen: Ventrites I–II completely setose, III–IV with an incomplete row of setose punctures, V with a complete row of punctures, VI bordered with long setae on apex. Stridulatory apparatus of tergite VII with 2 bands of finely carinae, interrupted by a mid-line nearly reaching the apical margin. Tergite VIII rugopunctate on sides, discal area weakly punctate or smooth. Aedeagus: Parameres in caudal view (Fig. 8C), basal half with rounded outer sides, middle area strongly constricted on sides, apical half with divergent lateral flaps. In lateral view, apex downcurved, obtuse (Fig. 9C).

Female (Fig. 3D). Body length: 23.8–27.1 mm. Body width: 14.5–15.0 mm. Female differs from male in the following aspects: Head: Frons with slightly convex basal area. Pronotum: Simple convex, anteriorly with a small apical tubercle followed by a shallow concavity confined to anterior area; anterior angles densely punctate; concavity densely covered with coalescent punctures (Fig. 10C); discal area moderately punctate. Legs: Inner protarsal claw simple, similar to outer claw. Abdomen: Ventrite VI triangular. Tergite VIII with subtrapezoidal shaped apical invagination, transverse about 7.9 times wider than long (Fig. 11C).

Geographic distribution: Brazil: Minas Gerais, Rio de Janeiro (Fig. 12C). Bothynus tricornis occurs in transitional areas between Atlantic rainforest and Cerrado, with some occurrence from the Brazilian Atlantic coastal rainforest. It is apparently a rare species, which has not been collected nor registered in literature since Endrödi (1969, 1985) (who also cited records from the states of Espírito Santo and Santa Catarina). Recently a population was found in the north of Minas Gerais.