Arhopala agelastus is a species of butterfly belong to the lycaenid family described by William Chapman Hewitson in 1862. It is found in Southeast Asia (Peninsular Malaya, Langkawi, Singapore and ssp. perissa Doherty, 1889 Burma, Mergui and Thailand)[1]
Male above deep glossy ultramarine blue; under surface almost exactly like that of perissa [now subspecies] which may be only a hardly separable form of it, but the postmedian band of the forewing beneath is not so uniform, more distinctly composed of separate spots. Hereby perissa is very similar to [related] forms which are difficult to separate from this species.[2]