Unexpected species richness of the lichen genus Protoblastenia (Lecanorales, Psoraceae) in Finland

The taxonomy of <i>Protoblastenia</i> in Finland was studied, based on morphology and molecular data (nuITS rDNA sequences). Twenty species were recognised, with sixteen species being newly described here: <i>P. arupii</i> <b>sp. nov.</b>, <i>P. borealis</i> <b>sp. nov.</b>, <i>P. compressa</i> <b>sp. nov.</b>, <i>P. dolomitica</i> <b>sp. nov.</b>, <i>P. ekmanii</i> <b>sp. nov.</b>, <i>P. fennoarctica</i> <b>sp. nov.</b>, <i>P. minuta</i> <b>sp. nov.</b>, <i>P. oulankaensis</i> <b>sp. nov.</b>, <i>P. pseudocompressa</i> <b>sp. nov.</b>, <i>P. pseudoterricola</i> <b>sp. nov.</b>, <i>P. remota</i> <b>sp. nov.</b>, <i>P. rikkinenii</i> <b>sp. nov.</b>, <i>P. saanaensis</i> <b>sp. nov.</b>, <i>P. timdalii</i> <b>sp. nov.</b>, <i>P. violacea</i> <b>sp. nov.</b> and <i>P. westbergii</i> <b>sp. nov.</b> All species are confined to calcareous rocks, except <i>P. terricola</i> which also grows on calcareous soil. The calcareous fells in Enontekiö in NW Finland were identified as hot spots of <i>Protoblastenia</i> diversity. Nine newly-described species (<i>P. arupii</i>, <i>P. fennoarctica</i>, <i>P. minuta</i>, <i>P. pseudoterricola</i>, <i>P. rikkinenii</i>, <i>P. saanaensis</i>, <i>P. timdalii</i>, <i>P. violacea</i> and <i>P. westbergii</i>) 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. <i>Protoblastenia rikkinenii</i> is reported from Norway and <i>P. oulankaensis</i> from Italy, based on GenBank sequences. Full descriptions and a preliminary key of <i>Protoblastenia</i> in Finland are provided.