*cebennaria (Gisin, 1956)
*dunaria (Gisin, 1956)
*fimetaria (Linnaeus, 1767) [not 1758] [INVALID NAME]
*imperfectus (Denis, 1938)
*pygmaea (Bagnall, 1937)
*wrighti (Carpenter, 1895)
*inermis (Tullberg, 1871)
Deuteraphorura cebennaria (known as Onychiurus fimetarius or Onychiurus cebennarius or Deutephorura inermis in earlier literature) appears to be a common and widespread species, but may be hiding a second species; it appears to be absent from northern Scotland.
Deuteraphorura inermis does not possess anal spines or a furca. The post-antennal organ (PAO) is elongate and contains about 12 to 15 complex vesicles (Fig. 1). The first thoracic segment (th1) has 1+1 dorsal pseudocelli (PSO) (Fig. 2). The tibiotarsus of the leg bears only nine distal setae. There is no inner tooth on the claw (only laterals), and males possess a field of only slightly thickened ventral setae on the third abdominal segment (abd3). The largest specimen Steve Hopkin examined was 2.4 mm in length. The typical PSO formula is 32/133/33354 but their number and arrangement on the body is extremely difficult to determine, especially in permanent slide mounts. In the specimens in the BMNH there have been numerous examples of asymmetry and it is clear that the PSO formula (sensu Gisin) needs to be treated with extreme care if it is to be used as a method of separating species. Several of the records are from caves, and one from groundwater from the Yorkshire karst.