Specimens of Cladoniaceae from 28 herbaria were studied using methods of classical herbarium taxonomy and thin-layer chromatography. Thirty-nine species, representing the genera Cladia, Cladina, and Cladonia, are recognized in the study area. Most species show a “bipolar or cosmopolitan” distribution pattern, and only four are endemic to the area. One-third of species belong to a so-called Southern Hemisphere element. Long-distance dispersal is considered to be the most important way of reaching new areas in the fragmented southern areas, past and present. Three species, viz. Cladonia archeri Stenroos (Macquarie I.), C. marionii Stenroos (Marion I.), and C. albata Stenroos (Prince Edward I.), are described as new. New synonyms are Cladonia subdigitata Nyl. and C. corallifera subsp. subdigitata Vainio (= C. ustulata), C. furcata var. subpungens Müll. Arg., C. patagonica A. Evans (= C. squamosa), and C. subantarctica Filson & Archer (= C. subsubulata). Nine of the present species (C. cf. cariosa, C. merochlorophaea (var. novochlorophaea), C. ochrochlora, C. phyllophora, C. cf. poeciloclada, C. subulata, C. sulphurina, C. cf. tapperi, and C. weymouthii) have not been correctly reported from the area before