Published online by Cambridge University Press: 14 November 2017
Rinodina is a widespread, polyphyletic genus of crustose Physciaceae with c. 300 species worldwide. A major missing link in understanding its global biogeography has been eastern Asia where the genus has never been systematically revised. Here we review specimen and literature records for Rinodina for north-eastern Asia (Russian Far East, Japan and the Korean Peninsula) and recognize 43 species. We describe two species, R. hypobadia and R. orientalis, as new to science. Rinodina hypobadia is distinguished by its pigmented hypothecium, Dirinaria-type ascospores and pannarin in both thallus and epihymenium. Rinodina orientalis is characterized by its erumpent apothecia that remain broadly attached, with discs sometimes becoming convex and excluding the thalline margins, ascospores belonging to the Physcia-type and secondary metabolites absent. Nine other species are reported from the region for the first time. These include R. dolichospora, R. freyi, R. metaboliza, R. sicula, R. subminuta and R. willeyi. Of particular biogeographical interest are three additional new records that have western North American–eastern Asian distributions: the corticolous species R. endospora, R. macrospora and R. megistospora. Six species have the better known eastern North American–eastern Asian distributions: R. ascociscana (syn. R. akagiensis, R. melancholica), R. buckii, R. chrysidiata, R. subminuta, R. tenuis (syn. R. adirondackii) and R. willeyi, and two have eastern North American–eastern Asian–European distributions: R. excrescens and R. moziana (syn. R. destituta, R. vezdae). Our study begins to close one of the largest gaps in our knowledge of circumboreal species distributions in Rinodina and, together with previous studies in North America and Europe, provides new insights into circumboreal crustose lichen biogeography. Rinodina cinereovirens (syn. R. turfacea var. cinereovirens) is also reported as new to North America.