Callipodida are long and narrow millipedes, up to 100 millimetres (3.9 in) in length with 40-60 body segments. A dorsal groove is present running down the mid-line of the body, and many species are ornamented with longitudinal crests or ridges. Sexually mature males possess a single pair of gonopods, consisting of the modified anterior leg pair of the 7th body segment, and carried concealed within a pouch.
The order Callipodida contains three suborders, seven families, and approximately 130 species. The genus Sinocallipus, which constitutes the suborder Sinocallipodidea, is thought to be the most primitive, and a sister group to all other callipodans.
^Stoev, Pavel; Enghoff, Henrik (2011). "A review of the millipede genus Sinocallipus Zhang, 1993 (Diplopoda: Callipodida: Sinocallipodidae), with notes on gonopods monotony vs. peripheral diversity in millipedes". ZooKeys90 (0). doi:10.3897/zookeys.90.1291.