Abstract
We analysed documented moss species numbers on a global scale with the aim to identify regions or countries with possibly under-documented moss floras. European units (countries, administrative units) in general have much higher documented species numbers than extra-European units with similar area sizes. Especially South American and African units have relatively low documented species numbers. This is in contrast to the overall continental moss floras of these regions, which are almost twice as species rich compared to Europe. We identified possibly under-documented geographical units in each continent based on negative outliers in species-area plots. There is a negative correlation of species richness with the area of desert or grassland biomes in a geographical unit. Based on our dataset, the question of the existence of a general latitudinal gradient of increasing moss diversity with decreasing latitude has to be denied