Organisation of the checklist - Distribution
For the estimation of distribution, we also use data which we did not check as well as unpublished data given by reliable colleagues, providing that we have seen at least some specimens of the species mentioned in those publications or reports. Any use of published or unpublished data for the estimation of distribution is thus supported by carefully testing whether our concept of the species is identical with that of authors of the chorological information considered for our checklist.
The distribution data provided are based on the number of localities where the corresponding taxon has been observed or collected. It is not an estimation of its abundance. A species occurring in a single locality is thus given as RRR whatever the number of thalli observed or its population levels or trends. However, the usual situation is that local and very restricted species have low population levels, whereas widespread species have healthy and abundant populations. Obvious exceptions are mentioned in the text, e. g. Lecanora silvae-nigrae is known from a single locality near Vielsalm (a natural scree of siliceous rocks), where it develops a healthy and abundant population.
The distribution data are based on reliable publications and reports, but may not correspond to the actual situation. Species like Lecanora conizaeoides or L. muralis are rarely published or mentioned in reports, but there is little doubt that they are widespread in most districts.