Opisthocheiridae

Millipedes in this family range from 5 mm to 16 mm in length. The paranota are small humps and hardly developed sometimes. The posterior gonopods have from one to three segments.^[3] Adult millipedes in this family have 26 or 30 segments (counting the collum as the first segment and the telson as the last).^[4][3] 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.^[5][4]

This family includes seven genera:^[1][2]

• Brachytropisoma Silvestri, 1898
• Ceratosphys Ribaut, 1920
• Hispaniosoma Ribaut, 1913
• Marquetia Ribaut, 1905
• Marquetiella Jeekel, 1969
• Opisthocheiron Ribaut, 1913
• Sireuma Reboleira & Enghoff, 2014