C. metallifer exhibits extreme sexual dimorphism, where males are larger than females and have long mandibles.

To compensate for the weakened bite force caused by their long mandibles, males of this species have larger head muscles than females.

[citation needed] The size of males varies greatly, with certain subspecies ranging from 26 to 100 millimetres in length.

[citation needed] To avoid breaking their jaws when biting, male C. metallifer have a high density of mechanoreceptors on their mandibles.

[citation needed] C. metallifer and all its subspecies are found in Indonesia, primarily on the Maluku Islands and Sulawesi.

[citation needed] C. metallifer has been used in genetic studies to determine the genes involved in its sexual dimorphism.

[14] Because the development of large mandibles involves numerous investments and trade-offs, there is an upper limit to their size.

These include jousting with their mandibles and forcefully biting, concluding with the loser being thrown off the tree and losing access to potential mates.

[14] Larger mandibles are advantageous in all of these interactions, and only males that are nearly evenly matched will advance past the early stages of competition.