Opisthocheiridae

Opisthocheiridae is a family of millipedes belonging to the order Chordeumatida. These millipedes range from 5 mm to 16 mm in length and are found from Belgium to Morocco. Adult millipedes in this family have 26 or 30 segments (counting the collum as the first segment and the telson as the last). This family includes the cave-dwelling species Opisthocheiron canayerensis, notable as one of only a few chordeumatidan species with only 26 segments in adults, four fewer segments than typically found in adults in this order. The adult female of this species has only 42 pairs of legs, and the adult male has only 40 pairs of walking legs, excluding two pairs of gonopods.

Genera:
 * Brachytropisoma Silvestri, 1898
 * Ceratosphys Ribaut, 1920
 * Fuentea Brölemann, 1920
 * Haplosphys Ribaut, 1920
 * Hispaniodesmus Verhoeff, 1910
 * Hispaniosoma Ribaut, 1913
 * Marquetia Ribaut, 1905
 * Marquetiella Jeekel, 1969
 * Opisthocheiron Ribaut, 1913
 * Proceratosphys Mauriès & Vicente, 1977
 * Sireuma Reboleira & Enghoff, 2014