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The endemic fauna of the sicilian islands 253

from 35° 30'N of Lampedusa, in Pelagie islands, to endemic taxa. It is a complex process, influenced
the 38° 50'N of Strombolicchio, in the Aeolian by a multiplicity of factors, above all taxa vagility
archipelago. The strait of Messina (approximately and paleogeographic evolution of the islands.
3 km of length in the narrowest point) currently (Whittaker, 1998). Generally, since the a drop in the
separates Sicily from Eurasia, while the portion dispersive capacities raises the possibilities of ge-
which is closest to the African Continent (Tunisia), netic isolation, groups of animals with scarce dis-
is about 70 km distant from the island of Pantelleria. persive capacities show higher levels of endemism
in confrontation with others with higher dispersive
Data gathering and elaboration capacity (Minelli et al., 2005).
By observing figure 5, as a confirmation to this
To propose a thorough summary we have anal- hypothesis, we can observe the absence of Diptera,
yzed the ample bibliography available today on the Odonata, Neuroptera and generally of groups char-
circum-sicilian islands. In particular, we have made acterized by a marked vagility among the 111 en-
reference to the works included in Zavattari (1960), demic taxa of the fauna of circum-sicilian islands.
Francini Corti & Lanza (1973), Massa (1995a), Well represented are the Gastropod Molluscs (20
Sparacio (1995, 1997, 1999), to the management taxa, 18%), whose scarce dispersive capacity is
plans of the natura 2000 sites “Isole Egadi”, “Isole well-known. As it is legitimate to expect, of the 111
Eolie”, ”Isole Pelagie”, “Isola Di Ustica”, “Pantel- taxa taken into consideration, about 50% is made
leria” (AAVV, 2009a, b, c, d), as well as to the up by Coleoptera, by far the most ecologically di-
dossiers of the checklist of Fauna d’Italia (Minelli versified group on a global level, constituting alone
et al., 1993–1995) and to the exquisite though in- over 20% of Italian fauna (Ruffo & Stoch, 2005).
complete Ckmap 5.4.1 (Stoch, 2006) (for the list of Among Coleoptera, as in figure 6, the largest fam-
the refence from which the taxa distribution has ilies are made up by Tenebrionids (18 taxa, 33%)
been drawn, see Fig. 6). As long as possible, we and Curculionids (16 taxa, 30%), two groups char-
have consulted the original description of the con- acterised by a strong tendency to insular differen-
sidered species bearing in mind the successive chro- tiation (Massa, 1995b).
nological, taxonomical and nomenclatural updates. The level of endemism in insular populations,
The reference nomenclature follows the checklist
of Fauna d’Italia (Minelli et al., 1993–1995), up- furthermore, is positively correlated to surface, hab-
dated case by case. We have attempted to sum up itat diversity, age and distance of the island from
data related to all the metazoans. However, only ad- the continent (Whittaker, 1998).
visory of endemic species referable to Arthropoda, To verify how much these factors influence the
Mollusca and Chordata have been taken into con- endemic contingents in the circum-sicilian islands,
sideration. Research related to other groups are now the number of endemic taxa of every island has
partial and incomplete. Some species present ex- been correlated to
clusively in the small islets that are perimetral to the 1) the distance from the nearest continental mass
major island have been included among these last (Sicily/Northern Africa)
ones. In particular, Anaspis akaira, known solely 2) maximum height (indirect index of habitat
for the Conigli islet, has been included among the diversity)
species of Lampedusa; Passalozetes paucesculptus, 3) surface. On the basis of the variable as in fig-
known for Basiluzzo, among the ones of Panarea. ure 6, a regression has been carried out, using the
The data has been organised in a database created Pearson index of correlation. From the results ob-
in a Microsoft Access 2007 environment, and elab- tained, we observe that neither the distance from the
orated with Microsoft Excel 2007. continent (r = 0.198) nor height (r = 0.235) are cor-
related to the number of endemic taxa (the Pearson
coefficient “r” is a measure of the correlation
DISCUSSION between the two viariables: it can variate between
+1 or -1 and it acquires these extreme levels if the
All the insular population, as effectively isol- correlation - positive or negative - is perfect, while
ated, may show more or less pronounced character- it acquires values close to zero if the two variables
istics which, in time, may lead to the formation of are independent). A weak correlation has emerged