Twenty-six lichen taxa are reported for the first time from either the Tierra del Fuego Archipelago, the Falkland Islands (Islas Malvinas), or both, from collections made by Henry Imshaug and his co-workers between 1968 and 1971 and now housed in the herbarium of Michigan State University (msc). Of these, Alectoria sarmentosa subsp. vexillifera, Bartlettiella fragilis, Micarea incrassata, M. melaena, Parmelia kerguelensis, Rhizocarpon infernulum and R. submodestum are reported for the first time from South America, and Alectoria nigricans, Brigantiaea fuscolutea, Buellia anisomera, B. subcervina, Caloplaca isidioclada, C. millegrana, Lecidella wulfenii and Megalospora tuberculosa are reported for the first time from Argentina or the Falkland Islands.