The Placynthium nigrum group in the Iberian Peninsula consists of P. dolichoterum (Nyl.) Trevis., P. garovaglii (A. Massal.) Malme, P. nigrum (Huds.) Gray, P. tantaleum (Hepp) Hue and P. tremniacum (A. Massal.) Jatta. Ecological and distributional data, and a discussion of diagnostic characters of taxonomic value are provided. All taxa are clearly differentiated by their ascospores. P. tantaleum and P. tremniacum are new to Portugal. From many species there are new records for several provinces.