Combing for beach broccoli: surveys of the endemic macrolichen Cladonia submitis determines endangered status under IUCN guidelines

The global decline in biodiversity has invigorated the field of conservation biology, leading to investigation of species at risk of extinction in hopes of generating effective conservation strategies. Some highly diverse taxa, such as lichens, have received considerably less conservation attention, compared to plants and vertebrates. Here we add present the results of a comprehensive demographic survey and IUCN risk assessment of Cladonia submitis, a conspicuous macrolichen endemic to the Mid-Atlantic coast of eastern North America, across the core of its range. While it was found at several new locations, we found the species had disappeared from many locations where it once occurred. This decline, in conjunction with its restricted range, supports a status of Endangered under IUCN guidelines. While fire and sea level rise likely pose threats to the species, the most immediate threat is urbanization and alteration of coastal dunes. This evaluation does not consider collections from Japan and Sakhalin Island which have been assigned as C. submitis, due to differences in range, habitat and morphology that suggest this identification is inaccurate. In the absence of a proper taxonomic assessment or phylogenetic study to answer this question of identity, Japanese specimens could not be considered in this assessment. Altogether, this study provides a basis for effective management strategies of this charismatic species whose core range consists of the densely populated region between the American cities of Boston and Washington, D.C.