Trigonopterus argopurensis

The beetle is 2.88–3.18 mm long. It has a reddish-brown head and legs, with the elytra also being reddish-brown but marked by a sinuate black transverse band. The rest of the body is black. The body is elongated, with a pronounced constriction between the pronotum and elytron when viewed from above, and a convex profile. The rostrum has a median and a pair of submedian ridges, with the grooves between them punctured and each puncture bearing an erect seta. The epistome is simple.^[1]

The pronotum narrows near the tip and has a densely punctured surface. Some punctures are elongated or arranged in merged rows forming rhombus-like patterns. Each puncture contains a long, white scale or seta. A smooth central ridge runs along the middle. The elytra have indistinct striae and flat intervals, with small, irregular punctures. Sparse rows of long, flat, cream-colored scales are present, and the spaces between them are finely textured. In the apical third, interval 7 forms a sharp lateral edge, and the sutural interval is swollen and slightly protruding at the tip. The femora have a crenulate ridge on the underside that ends in a blunt tooth. The metafemur has a stridulatory patch near the tip. The upper edge of the tibiae has a simple angled projection near the base. The metatibia lacks a premucro at the tip. Abdominal ventrite 5 is flat and coarsely punctured.^[1]

The penis has nearly parallel sides and a rounded apex with a short central extension. The transfer apparatus is compact, with sickle-shaped processes and a smoothly curved ventral profile. The apodemes are 2.4 times the length of the penis body. The ductus ejaculatorius lacks a bulbus.^[1]

In females, the rostrum has smooth median and submedian ridges. The elytral apex is rounded in males and narrower and angled in females. Female abdominal ventrite 5 is flat.^[1]

Trigonopterus argopurensis is endemic to the Indonesian province of East Java, where it is known only from Mount Argopuro. It has been recorded from elevations of 1,457–1,785 m (4,780–5,856 ft).^[1]