T. castaneus T. claremontus T. deses (type) T. loomisi T. monachus T. uncigerus T. utahensis Auxobolus Californibolus Tylobolus is a genus of millipedes in the order Spirobolida with seven known species found in western North America.

[1] All species of Tylobolus occur on the Pacific Slope of North America, ranging from Washington state to Baja California, Mexico.

[3] An additional species, "T. fredericksoni", was previously thought to occur in Kansas and Nebraska, but its existence is dubious, and may be attributable to Narceus americanus, a spirobolid common in the eastern U.S.

[5] Tylobolus may be one of the most advanced genera of the family Spirobolidae, in terms of a number of traits it possesses that are absent or poorly developed in other spirobolids.

Of the two, Tylobolus is thought to be the more advanced due to more complex genital morphology, and a prominently hooked projection of the third pair of legs in males.