Three overlooked species of Bacidia from insular Laurimacaronesia

We discuss the taxonomy of three species of Bacidia occurring in insular Laurimacaronesia. Two of them, B. amylothelia (Vain.) Vain. and B. endoleucoides (Nyl.) Zahlbr., which were previously described from Angola and Madeira, respectively, are found here to belong in Bacidia s. str. (Ramalinaceae). Modern descriptions and illustrations are provided for the first time. Bacidia amylothelia is similar to B. areolata Gerasimova & A. Beck, B. campalea (Tuck.) S. Ekman & Kalb, B. fusconigrescens (Nyl.) Zahlbr., B. heteroloma (Vain.) Zahlbr., B. millegrana (Taylor) Zahlbr. and B. suffusa (Fr.) A. Schneid. and is reported here from the Canary Islands. Bacidia endoleucoides is most likely to be confused with B. absistens (Nyl.) Arnold, B. friesiana (Hepp) Körb., B. salazarensis B. de Lesd. and B. caesiovirens S. Ekman & Holien and was found to be widely distributed in the Canary Islands and Azores in addition to Madeira. The third species, Bacidia deludens S. Ekman, Tønsberg & van den Boom, is described here as new to science. Bacidia deludens is characterised by a greyish, crustose thallus with whitish soralia, pale apothecia with crystals in the hymenium and proper exciple, acicular ascospores with 3–19 septa, and the production of fumarprotocetraric acid as the consistently present major substance. It is described here from the Canary Islands and Madeira. Although conservatively treated here in Bacidia, we argue that it is likely to belong in the Malmideaceae. An identification key to all known species of Bacidia s. str. in insular Macaronesia is provided.