About Xylotrupes gideon (Linnaeus, 1767)
Xylotrupes gideon adults reach a body length of 3.5–7 centimeters (1.4–2.8 inches). Like other rhinoceros beetles, this species shows strong sexual dimorphism: males are larger than females. Males have two chitinous, bifurcated horns: a thick thoracic horn and a smaller cephalic horn, which they use to fight off rival males during mating season. This species has a shiny coloration that can be dark red, dark brown, or black. Its eyes are positioned on either side of the head. When disturbed, these beetles produce a hissing noise by rubbing the tip of their abdomen against the edge of their elytra. Male Xylotrupes gideon have a transverse head with sparse punctures; their clypeus is elongated, with sparse, minute punctures. Their antennae have 10 segments. The pronotum and scutellum also have sparse, minute punctures. The elytra and pygidium are coriaceous, with fine, sparse punctures. Females have a rugose dorsum, with a pronotum marked by coarse, dense punctures. The female pygidium is finely rugose. This species is widespread across India, Sri Lanka, Thailand, Indonesia (including Java, which hosts the nominotypical form, and Borneo, which hosts the subspecies borneensis), the Sunda Islands, and the Moluccas.
