A new species of the genus Pseudidothea Ohlin, 1901 is described from the Burdwood Bank area (South Orkney Islands). It has been collected during the SO-AntEco JR15005 RRS James Clark Ross expedition under the lead of the British Antarctic Survey (BAS). The new species, Pseudidothea armata sp. n., is very similar to P. scutata (Stephensen, 1947); however, it is characterised by peculiar supra-ocular spines and a different tubercular pattern. The study of the species of the Pseudidothea helps to better understand the diversity of the Pseudidotheidae in the Southern Ocean.