Lyperobius clarkei has a black body with pale yellow/white scales which are at their most dense on the pronotum, head and on the elytral intervals. These white scales form stripes on the abdomen. Its body ranges in length from 20.5–28 mm. This species is sympatric with Lyperobius fallax, but can be distinguished by its larger size. Like other New Zealand Molytinae, this weevil is flightless. Its larvae have a creamy-white body with a dark red-black head.
The only known host plant for this species is Aciphylla ferox.Adults of other Lyperobius species browse on leaves, flower stems and seeds of ''Aciphylla.''