Abstract The most effective way of mapping species diversity, is to choose an abundant, sedentary, small and widespread taxon, such as rodents are. At present, thanks to a recent improvement of karyology and genetics, knowledge is growing faster at the macro - regional level than at the local level. This is due to a delay in assessing the whole territory. In fact new findings often come from one or very few and small localities. This implies new problems in mapping species richness. Indeed today, even less than in the past, Richness can be evaluated directly by the crude species number, without any kind of standardisation of data a/o weighing. A study of maps of Italian rodents has shown that the more up to date the maps are, the more they coincide with theoretical calculations based on consolidated ecological and biogeographical rules. Richness maps (i.e., weighted and standardised species number) show an even more satisfactory representation of the general geo-ecological outline of the Italian peninsula and its subpeninsulae.