Rhodopetoma diaulax is a species of sea snail, a marine gastropod mollusk in the family Pseudomelatomidae.

The axial sculpture consists of rather strong irregular incremental lines.

The spiral sculpture consists of a thickened band between the suture and the somewhat constricted anal fasciole.

On the body whorl in front of the angulation there are about 18 threads growing smaller and more close-set anteriorly.

[2] This marine species occurs off Santa Rosa Island, California.