Adult C. yosemitensis reach lengths of up to 11 cm (4.3 in) and up to 80 body segments. The species is characterized by a broad yellow or orange dorsal band that extends from the collum (first body segment) to the telson, with a bold black stripe down the middle of the band. The base body color is black. The simple eyes (ocelli) are arranged in patches on each side of the head, each patch consists of four rows of ocelli.