The lichen genus Umbilicaria in Ecuador

Nine species of the saxicolous lichen genus Umbilicaria from Ecuador are reported and a key is provided: U. africana, U. aprina, U. cinereorufescens, U. decussata, U. dendrophora, U. haplocarpa, U. leprosa, U. nylanderiana and U. vellea. The species diversity of this genus on the equatorial high mountains of South America is low compared to North America and Eurasia, but similar to that found on high African peaks close to the equator. The species mostly belong to a high-alpine element with worldwide distribution. Two species belong to an Andean endemic element, viz U. haplocarpa and U. leprosa. The low diversity and low percentage of endemism may reflect the fairly recent uplift of the Andes and the comparatively small geographic extent of the alpine Andean biota. The dense rainforests of Ecuador leave few suitable open rock habitats for the establishment of these light-craving lichens below the tree-line (4000-4200 m a.s.l.), and thus their equatorial habitat is almost exclusively restricted to the alpine zone between the tree-line and the snow-line (4700-4800 m a.s.l.). The equatorial species mainly reproduce asexually by thalloconidia, and the adaptive significance of this type of reproduction in high altitude habitats is discussed.