The taxonomy of Protoblastenia in Finland was studied, based on morphology and molecular data (nuITS rDNA sequences). Twenty species were recognised, with sixteen species being newly described here: P. arupii sp. nov. , P. borealis sp. nov. , P. compressa sp. nov. , P. dolomitica sp. nov. , P. ekmanii sp. nov. , P. fennoarctica sp. nov. , P. minuta sp. nov. , P. oulankaensis sp. nov. , P. pseudocompressa sp. nov. , P. pseudoterricola sp. nov. , P. remota sp. nov. , P. rikkinenii sp. nov. , P. saanaensis sp. nov. , P. timdalii sp. nov. , P. violacea sp. nov. and P. westbergii sp. nov. All species are confined to calcareous rocks, except P. terricola which also grows on calcareous soil. The calcareous fells in Enontekiö in NW Finland were identified as hot spots of Protoblastenia diversity. Nine newly-described species ( P. arupii , P. fennoarctica , P. minuta , P. pseudoterricola , P. rikkinenii , P. saanaensis , P. timdalii , P. violacea and P. westbergii ) are restricted to this area in Finland. Several of the species are semi-cryptic. On average, they may have minor morphological differences, but many specimens cannot be identified, based on morphology only. Protoblastenia rikkinenii is reported from Norway and P. oulankaensis from Italy, based on GenBank sequences. Full descriptions and a preliminary key of Protoblastenia in Finland are provided.