Idionyx rhinoceroides is a species of dragonfly in the family Synthemistidae. It is known only from a single female collected from type locality (Dhoni, Palakkad, Kerala) in the Western Ghats of India.[1]
It is a small dragonfly with emerald-green eyes. Its thorax is metallic emerald-green, coated with yellow hairs on dorsum. Humeral stripe is absent. There is a narrow oblique citron-yellow stripe traversing the spiracle and another bordering the lower part of metepimeron. Beneath the side is yellow, with an oblique bluish-black stripe and a triangular blackish-brown spot. Abdomen is black. The ventral borders of segments 2 and 3 are citron-yellow.[2]
This species can be easily distinguished from all other species by the unique shape of its vesicle.[2]