Macrosternodesmidae

In 1916, the French myriapodologist Henry W. Brölemann proposed Macrosternodesmini as a tribe to include the monotypic European genus Macrosternodesmus,^[10] which he had described earlier in 1908.^[11] In 1980, the American biologist Richard L. Hoffman elevated this tribe name to family status as Macrosternodesmidae.^[12][13] In 2013, however, the Russian zoologist Sergei I. Golovatch deemed Macrosternodesmidae to be a junior synonym of Trichopolydesmidae.^[8] In 2017, the biologists William A. Shear and James M. Reddell rejected this proposed synonymy and retained Macrosternodesmidae as a valid family mostly endemic to North America but also including Macrosternodesmus and three other monotypic European genera.^[14]

Authorities often consider Nearctodesmidae to be a junior synonym of Macrosternodesmidae.^[15][8] In 2017, Shear and Reddell placed the genera previously assigned to the family Nearctodesmidae in a new subfamily Nearctodesminae in the family Macrosternodesmidae.^[14] Others have adopted this proposed revision.^[16][17] In 2019, Shear, Rowland M. Shelley, and David B. Steinmann proposed two new genera (Packardesmus and Coloradesmus) and placed them in the other subfamily (Macrosternodesminae) in this family.^[18][12] Some authorities accept Macrosternodesmidae as a valid family but nevertheless place Macrosternodesmus, Packardesmus, and Coloradesmus in the family Trichopolydesmidae instead.^[1][19]

As described by Shear and Reddell based on North American species, the millipedes in this family feature a small collum shaped like a transverse oval and well developed paranota. Species in this family range from white to brown or red.^[14] Whereas millipedes in the subfamily Macrosternodesmidae are small (2.5 mm to 12 mm in length) and often lack pigment,^[12] those in the subfamily Neactodesminae are much larger (10 mm to 35 mm in length) and often brown, orange, pink, or red.^[18] Whereas Macrosternodesmines feature short antennae with bulbous distal segments, Nearctodesmines feature long antennae with cylindrical distal segments.^[12] The tergites feature setae that are often arranged on rows of tubercles in Macrosternodesmines, but these surfaces are entirely smooth and lack setae in Nearctodesmines.^[14][12]