Color is highly variable in this genus, both among and within species.[5] The dorsal integument ranges from blue black to slate grey or brown, and the ventral integument ranges from creamy white to brown. The number of legs in this genus range from 16 pairs (e.g., in O. cinctipes) to 18 pairs (in O. roseus). Velvet worms in this genus use the last pair of legs in walking. This leg pair is fully developed, with claws and four pads on each foot.[6] The feet in this genus feature three distal leg papillae: one anterior, one posterior, and one median.[7] The genital opening is located between the last pair of legs.[5] The male genitalia feature a cruciform opening and four pads; the female genitalia feature a longitudinal opening.[6]
Reproduction
Mothers in this genus give birth to live young.[8] In particular, this genus exhibits matrotrophicviviparity, that is, mothers in this genus retain eggs in their uteri and supply nourishment to their embryos, but without any placenta.[9] The young are born tail first, one or two at a time. The young resemble adults in form but are smaller.[7]
^Mayer, Georg; Bartolomaeus, Thomas & Ruhberg, Hilke (2005). "Ultrastructure of mesoderm in embryos of Opisthopatus roseus (Onychophora, Peripatopsidae): Revision of the 'long germ band' hypothesis for Opisthopatus". Journal of Morphology. 263 (1): 60–70. doi:10.1002/jmor.10289. PMID15536644. S2CID33663506.
^Mayer, Georg; Franke, Franziska Anni; Treffkorn, Sandra; Gross, Vladimir; de Sena Oliveira, Ivo (2015), Wanninger, Andreas (ed.), "Onychophora", Evolutionary Developmental Biology of Invertebrates 3, Vienna: Springer Vienna, pp. 53–98, doi:10.1007/978-3-7091-1865-8_4, ISBN978-3-7091-1864-1, retrieved 2023-02-15