About Orthomorpha coarctata (Saussure, 1860)
Male Orthomorpha coarctata measure 14.5–20.5 mm in length and 1.5–2.7 mm in width, while females are somewhat larger at 16.5–27.5 mm long and 1.6–3.2 mm wide. This species can be distinguished from Oxidus gracilis, another widely introduced Asian millipede, by having proportionally longer, pointier paranota (lateral keels) on mid-body segments, and longer male gonopods (reproductive appendages). Within the genus Orthomorpha, O. coarctata is unique because its gonopods have a single, simple tip, while other species in the genus have gonopods with two or three lobes. This distinct trait has led some authors to place O. coarctata in a separate, monotypic genus called Asiomorpha.
