Miriquidica invadens, an obligate youth parasite on Sporastatia, with remarks and a key to species of the M. griseoatra-group

The new species Miriquidica invadens Hafellner, Obermayer & Tretiach is described and reported from Austria, Bulgaria, Italy, Switzerland, France and Spain. From the morphological point of view the species belongs to the M. griseoatra-group in which it is so far the only constantly lichenicolous taxon. It starts its ontogenetic life cycle as an obligate youth parasite on Sporastatia, mostly upon S. polyspora. Morphoanatomic treatments of other species of the Miriquidica griseoatra-group occurring in Europe based on the examination of type material are presented too. According to the characters exhibited by the lectotype of Lecidea contigua var. griseoatra Flot., M. griseoatra (Flot.) Hertel & Rambold is the correct name for a montane species with comparted areoles and immersed, laterally adnate apothecia with a pigmented hypothecium. Specimens exhibiting this set of characters usually were named M. obnubila auct. According to the characters exhibited by an isotype of Lecidea (Biatora) obnubila Th.Fr. & Hellb., M. obnubila (Th.Fr. & Hellb.) Hertel & Rambold is a species with sessile apothecia with a hyaline hypothecium. Lecidea subplumbea Anzi does not constitute a heterotypic synonym of Lecidea griseoatra (Flot.) Schaer. but is the legitimate name on species level for Miriquidica griseoatra sensu auct., therefore M. subplumbea (Anzi) Cl.Roux is the correct name for that taxon. Lecidea inserena Nyl. is confirmed as heterotypic synonym of Lecidea subplumbea Anzi. Lecidea plumbea Garov. is an earlier heterotypic synonym of Miriquidica limitata Hertel & Rambold, therefore the new combination M. plumbea (Garov.) Hafellner, Obermayer & Tretiach is introduced. For Lecidea contigua var. griseoatra Flot., Lecidea inserena Nyl., Lecidea plumbea Garov., and Lecidea subplumbea Anzi lectotypes are designated.