Arthurdendyus testaceus is a species of land planarian belonging to the tribe Caenoplanini. It is native to Australia and New Zealand.
The body of Arthurdendyus testaceus is long and tapers to a point at each end; it is around 7âÂÂ8 cm in length. It lacks eyespots. The dorsal side is a red color, ranging from a dull brick-red to a bright cherry-red. The ventral side is yellow.