The chorotypes of the Italian fauna.

The geographic distribution of animals and plants can be synthetically expressed by chorotypes. These are categories derived from a classifi cation based on distribution models, which are deducted by the compared analysis of species areas. Chorotypes have been widely used by zoologists from the beginning of 1900, but not all the authors agreed on the meaning of chorotypes and on the relative terminology. The same chorological term was used by different authors to indicate: (1) a recurring model of geographical distribution; (2) a group of species with certain ecological requirements within a selected geographical area; (3) a group of species which presumably have a common biogeographical history; (4) a group of phylogenetically closely related species with a common area of origin; (5) a group of species living in a certain biogeographical region, defi ned by climatic and phytogeographic criteria. The scheme adopted herein corresponds to the fi rst of the criteria listed above, as in Vigna Taglianti et al. (1993, 1999), and it is similar to the one used by La Greca (1964, 1975), who underlined the importance of defi ning chorotypes based on the similarity of distribution models shared by a large group of species. This approach is not meant to identify the historical factors that caused the actual distribution of the species, but to describe the distribution models. The similarity among species areas can be related to different palaeogeographic and ecological events, such as vicariance or dispersal phenomena. Because the distribution areas of the species is the base unity of biogeographical studies, a classifi cation based on unambiguous and precise terminology is the reference point for any further comparative study. The new classifi cation of chorotypes, as proposed by a group of specialists of terrestrial and freshwater Palaearctic fauna (Vigna Taglianti et al., 1993, 1999), is based on the following criteria: (1) defi ne a reduced number of chorotypes that include all the models of area distribution for the fauna under account; (2) eliminate all the ambiguous terminology; (3) go beyond the “Eurocentric” terminology, and focus the attention on the geographic distribution of each chorotype; (4) attribute a numerical code and an acronym to each chorotype which can be used for databases, and to create easily understandable and comparable ranges of chorotypes. List and description The main chorotypes of the W-Palaearctic fauna are listed below divided in 5 groups. The Cosmopolite (0.01, COS), Sub-cosmopolite (0.02, SCO), Endemic and Subendemic (4-digit code) elements must be added, case by case, to the main chorotypes on the basis of phylogenetic affi nities. The W-Palaearctic chorotypes absent from the Italian fauna are not included (such as the SW-Asiatic, N-European, Saharan.), but some chorotypes present only marginally are indeed included (Saharo-Sindian). 1. Chorotypes of species widely distributed in the Holarctic region 1.01. OLA. Holarctic: species distributed in both the Palearctic and Nearctic Regions. 1.02. PAL. Palearctic: species widely distributed in the Palearctic Region (Eurasia, extending South to the Himalayan range, North to Africa and Macaronesia). 1.03. WPA. W-Palearctic: species widely distributed in Europe to the Urals, SW Asia, N Africa and Macaronesia. 1.04. ASE. Asiatic-European: species widely distributed in Eurasia, extending south to the Himalayan range. 1.05. SIE. Sibero-European: species distributed in Siberia and Europe (including the Boreoalpine disjunct distribution). 1.06. CEM. Centralasiatic-European-Mediterranean: species distributed from the Gobi desert to Europe and N Africa. 1.07. CAE. Centralasiatic-European: as CEM, N Africa excluded. 1.08. CAM. Centralasiatic -Mediterranean: as CEM, Central Europe excluded. 1.09. TEM. Turano-Europeo-Mediterranean: species distributed in Europe (mostly Central and Southern Europe), N Africa, Middle East, Anatolia, Iran, Caucasus and Western Turkestan. 1.10. TUE. Turano-European: as TEM, N Africa excluded. 1.11. TUM. Turano-Mediterranean: as TEM, Central Europe excluded. 1.12. EUM. Europeo-Mediterranean: species distributed in Central and Southern Europe and in the Mediterranean basin.