This species’ identity was settled and a neotype designated by Knight (2013) who also revalidated the congener P. canius (Hamilton, 1822) and described the closely-related P. aurea.

These three had previously been considered to represent geographic forms of P. gelius, albeit on a tentative basis, with the validity of P. canius having been discussed since the late 19th century.

Generally considered to have an enormous natural range extending from Iran to Taiwan and Bali, with records existing from Iran, Iraq, Afghanistan, Pakistan, Nepal, India, Sri Lanka, Bangladesh, Bhutan, China, Myanmar, Thailand, Laos, Cambodia, Vietnam, Malaysia, Indonesia, and Singapore.

However there exists significant evidence to suggest that C. gachua as currently understood represents a complex of similar-looking species, and a taxonomic review of the group is clearly required.