In the Antarctic botanical zone the genus Ditrichum Hampe (Ditrichaceae, Bryopsida) is represented by three species, D. austro-georgicum (Card.) Seppelt, D. brotherusii (R. Br. ter.) Seppelt and D. lewis-smithii Ochyra sp. nov. The latter is closely related to D. immersum Zanten from the sub-Antarctic. However, D. lewis-smithii differs in its gymnostomous capsules, smaller, erecto-patent to widely spreading leaves with flexuose subulae, bistratose lamina cells at the leaf shoulders and mostly 2-3-stratose lamina in the subula. It is an epigean moss growing on bare ground and on soil covering rock ledges and on humus in rock fissures. It has been recorded so far only from the King George and Livingston Islands in the South Shetland Islands as well as from Signy Island in the South Orkney Islands and must therefore be considered an Antarctic endemic.