Peripatopsis stelliporata sp. nov. from South Africa is described. SEM observations are used to illustrate the similarities and differences between this species and Peripatopsis capensis Grube 1866. The most conspicuous differences in morphology between the two species relate to the structure of the last reduced pair of legs, and the male genital pore, which in P. stelliporata is stellate in shape. Maintaining P. stelliporata in culture allowed timings of births to be recorded and the onset of sexual maturity to be determined. Spermatophores were first noted when the males were c. 4 months old. Females were observed to give birth at 15 months of age. In any female the embryos are all at around the same stage of development, and females gave birth between February and May. Young were born singly or in pairs at intervals of several days. The appearance of the embryos of P. stelliporata and also those of P. capensis collected in 1996 and 1997 was unexpected, as they are transparent apart from the red pigmented gut running from the mouth to the anus. Previously observed embryos of P. capensis were opaque and unpigmented. In appearance these embryos have similarities to those of Opisthopatus cinctipes Purcell 1895, which exhibits a different pattern of embryonic development. Whether or not this difference in appearance of the embryos reflects a transition in the pattern of development is discussed. A modified key for South African Peripatopsidae incorporating P. stelliporata is presented.