Type species. Microarcturus tannerensis Schultz, 1966, herein designated and by monotypy.
Diagnosis. Head, pereonites and all pleonites each with transverse rows of submedian, sublateral and lateral tubercles bearing bead-like spheres; pleotelson with short oblique lateral tubercles. Eyes absent. Male pleopod 1 exopod with well defined groove opening at notch about three-quarters along, without ventral tooth.
Etymology. For California, combined with Arcturus, a commonly used genus stem.
Remarks. Microarcturus tannerensis Schultz, 1966 has remained without a valid genus name for almost 50 years, Microarcturus being a nomen nudum (Poore 2003). The species is still known only from its holotype. Its unique male pleopod 1 does not allow it to be placed in any known valviferan genus. The setation of pereopods 2– 4 excludes the species from Antarcturidae and other similar families.