[3][4] The specific name, swinhonis, is in honour of Robert Swinhoe, a British diplomat and naturalist stationed in China in mid-19th century,[4] who collected the holotype.

The medium to large eye has a dark grey-brown iris and a round, jet black pupil surrounded by a grey ring.

The body is dorsally dark grey-brown with ill-defined or fairly prominent square areas of black.

[3] R. swinhonis is non-venomous and docile; when threatened it may expand its throat and neck transversely, but is unlikely to bite.

It has nuchal glands that secrete a brown liquid; this may act as a predator deterrent, although its precise function remains unknown.