In this paper, four Antarctic species of the diatom genus Licmophora namely L. antarctica M. Peragallo, L. belgicae M. Peragallo, L. gracilis (Ehrenberg) Grunow and L. luxuriosa Heiden are described using an electron microscope, based on two collections of samples collected during different expeditions under the Brazilian Antarctic program (Summer of 1994, and 2003 to 2010). Plankton and benthic samplings were carried out at different locations in King George and Elephant Islands, Antarctic Peninsula. The fi ne morphologies of three endemic species, L. antarctica, L. belgicae and L. luxuriosa, are described, including information on structures like rimoportula, poroids and multiscissura. L. gracilis was also examined for confi rmation of its identity. Comparisons with allied species are also provided, as well as their geographic distribution around the Antarctic Peninsula.