Pseudotanais jonesi

Males of Pseudotanais jonesi are approximately 1 millimetre (0.04 in) long, while females are 0.8–1.0 mm (0.03–0.04 in) long.^[2] There are neither eyes nor ocular lobes on the head.^[2] Males are very similar to P. forcipatus, which is the only other species in the family to occur around the British Isles.^[2] In females, the cephalothorax is about 1.5 times as wide as it is long, and is triangular.^[2] Both the endopodite and the exopodite of the females' uropods are two-segmented, while males have a three-segmented endopodite.^[2]

Pseudotanais jonesi has only been discovered at a few sites around the British Isles. It is reported to be "fairly common"^[3] off the Isle of Man, where it lives in muddy substrates at depths of 32–90 metres (105–295 ft); it also occurs at depths of 20–38 m (66–125 ft) in Loch Creran and the Lynn of Lorn in western Scotland.^[2]