Rhyssonotus nebulosus, commonly known as the Brown Stag Beetle or Marbled Stag Beetle, is a species of stag beetle (family Lucanidae) native to eastern Australia.
 
Physical Characteristics
Appearance: They are typically small to medium-sized (25–35 mm) with a robust, mottled brown and black pattern that provides excellent camouflage against bark and leaf litter.
Sexual Dimorphism: Males possess prominent, antler-like mandibles used for wrestling other males, while females have much smaller mandibles.
Texture: The exoskeleton is often described as glossy or textured, though it may appear duller when wet. 
 
Habitat and Distribution
Native Range: Found primarily in Queensland and New South Wales, Australia.
Introduced Range: It has also been introduced into New Zealand.
Environment: They thrive in forested areas and are frequently found under rotting logs or decaying tree stumps. 
 
Diet and Behavior
Adult Diet: In the wild, they feed on sap and organic matter; in captivity, they readily consume soft fruits like bananas, apples, and melons.
Larval Diet: Larvae (grubs) develop in and feed on decaying white-rotten wood.
Behavior: Known to be relatively placid and slow-moving, they are often described as "hardy" and "beginner-friendly" for insect hobbyists. 
 
Captivity and Breeding
As of 2026, R. nebulosus remains one of the few species in its genus that is successfully bred in captivity. 
Breeding Needs: They require moist "flake soil" and soft decaying logs for egg-laying (oviposition).
Lifecycle: They have a relatively fast development time compared to other stag beetles, making them popular for captive rearing.