Medium-sized beetle (length 11.0 mm, width 6.3 mm) with strongly shiny, blackish-brown body (Fig. 1).

Figure 1.  

Orphnus drumonti, female, habitus. Scale 1 mm.

Clypeus widely rounded anteriorly, obtusely rounded laterally. Genae very small, not protruding past eyes. Anterior part of clypeus with low transverse ridge occupying about 1/3 width of clypeus. Dorsal side of head smooth with a few coarse punctures near eyes (Fig. 2).

Figure 2.  

Orphnus drumonti, female, head. Scale 1 mm.

Pronotum trapezoidal, with rounded lateral margins, about 1.8 times wider than long, convex, without excavations or ridges. Dorsal surface of pronotum with minute, feebly visible punctures throughout and with sparse, coarser punctures mostly laterally on disc. Lateral sides somewhat crenulate in dorsal view. Anterior margin with wide border and row of coarse punctures on disc along border. Basal margin with fine border and row of longitudinally elongated punctures along border.

Elytra strongly convex, with rows of large punctures along striae. Elytral intervals convex, with fine sparse punctation.

Scutellum rounded apically, smooth, about 1/11 the length of elytra.

Wings fully developed.

Anterior tibiae with 3 long outer teeth and a robust apical spur. Lateral margin basad of outer teeth not crenulate. Ventral surface of anterior tibiae smooth with two rows of setae along sides and a few very long setae in the middle. Middle and posterior legs similar in shape; posterior femora and tibiae about 1/8 longer than the middle ones. Middle and posterior femora almost impunctate, with 2 apical spurs; inner margin slightly concave with one transverse keel.

Abdominal sternites irregularly punctate, pubescent with sparse long setae. Visible sternite 6 as long as sternites 4–5 together in middle.

Pygidium semi-hidden under elytra, with sparse punctures and sparse long setae.

Female differs from male in having distinct protibial spur, relatively wider elytra, low transverse clypeal carina, and convex pronotum without excavations or ridges. Male have no protibial spur, narrower elytra (about as wide as pronotum), deep pronotal excavation with long ridges aside, and long, apically bifurcated clypeal horn (Fig. 3).

Figure 3.  

Orphnus drumonti, male, head. Scale 1 mm.

Body (Fig. 5) strongly convex, black, glabrous, length 4.7–5.5 mm.

Figure 5.  

Delopleurus naviauxi, male, habitus. Scale 1 mm.

Clypeus quadridentate. All four clypeal teeth acute, two medial ones relatively slender. Head without carinae on disc, small carinae present near inner margin of eyes. Genae right-angled, indistinctly separated from clypeus. Frontoclypeal and genal suturae indistinct. Eyes small, their dorsal parts slit-shaped, ventral parts sub-rectangular. Clypeus rugose in anterior part and laterally, frons densely punctate with elongate punctures.

Pronotum trapezoidal, about 2 times wider than long. Anterior and lateral margins bordered, base without border. Pronotum relatively densely punctate on disc (punctures separated by 1-2 puncture diameters), punctation becoming denser laterally.

Elytra trapezoidal, as wide as long, shiny. Striae distinct, with punctures larger than striae. Elytral intervals slightly convex on disc, with minute punctation.

Anterior tibiae with 3 outer teeth and a small acute tooth between 1st outer tooth and apical spur (Fig. 6).

Figure 6.  

Delopleurus naviauxi, male, protibiae. Scale 1 mm.

Pygidium with relatively slender borders and convex disc (Fig. 7). Basal border slender and almost parallel-sided except in the middle. Apical border about 2 times thicker in the middle than the basal border, becoming more slender laterally. Disc glabrous, punctate with punctures separated by 1–2 puncture diameters.

Figure 7.  

Delopleurus naviauxi, male, pygidium. Scale 1 mm.

Aedeagus of typical scarabaeine shape (Fig. 8). Phallobase with two symmetrical tubercles dorsally. Parameres symmetrical, without setae apically, rounded in lateral view.

Figure 8.  

Delopleurus naviauxi, male, aedeagus in dorsal and lateral view. Scale 1 mm.

Male differs from female in having pygidium with relatively large disc without visible setae as opposed to being with a deep transversal slit-shaped fossa with yellowish setae in female.