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F. Marrone et al., Ecology and distribution 2t53

Turanic-European taxon, which reaches in Sici- ness (n : 7). The second is located in the right
ly its south-westernmost areal limit. part and collects three species. Temporal di-
A. kerkvrerzsis has been collected in two small mension is negatively correlated with axis I (r
(8 -t and 40 m2) and turbid temporary water : -0.90), whereas permanency is positively re-
bodies, located at the edge of a vineyard, on a lated (r: 0.91). These two variables are strictly
lavic substratum at the foot of Etna Volcano, linked to altitude, area and macrophyte cover-
850 m a.s.l. These pools show conductivity val- ing. In Sicily, temporary ponds are generally lo-
I
ues of 490 and 450 pS cm respectively. A. cated higher above sea level, have a smaller
kerkvrensis was up to now known from Corfu area and show a richer macrophyte covering
Island Macedonia, Bulgaria and former Yu- compared to permanent environments. The sec-
goslavia (Dussnnr & DErnye 2002'), where it is ond tendency is vertical and linked to conduc-
typical of lowland astatic swamps and fish tivity values and separates environments with
I
ponds (R,tNcn Rpony 1994). As for the previ- conductivity values < 4 mS cm (group B)
ous species, Sicily represents its south-western- fiom those with values ranging between 4 mS
most areal limit. and 42 mS cm-r (group A). Thus, the perma-
Mixodiaptomus kupelwieseri was sampled nent water bodies lying on the right part of the
both in temporary and semi-permanent ponds plane are ranked according to increasing con-
characterized by rather low conductivity values ductivity values and the species associated re-
(50-390 trrS cm l;, limpid water, siliceous sub- flect this tendency showing Copidodiaptomus
stratum and at altitude ranging between 600 numidicus, Calanipeda aquaedulcis and Arcto-
and 1300m a.s.l. All the sites lie inside wooded diaptomus salinus distributed along this gradi-
areas, with the exception of two ponds, lying ent.
respectively in a cornfield and in a pasture land, The group of animals linked to temporary
both of them near to a wooded area and defor- waters seems to be more characteristic of a se-
ested only in the last decades. M. kupelwieseri mi-arid region like Sicily, as confirmed by the
is typical of central and southern Europe, while higher species richness and diversity of
in southeastern Europe it coexists with the calanoid assemblages. Moreover, a similar ten-
strictly related M. lilljeborgi, whrch replaces it dency has been observed for branchiopods also
in Northern Africa (Dussnnr 1989. Dussnnr & (Mnnnoxn unpub. data).
DEpRyE 2002).
Some biogeographical considerations on
Relationships with environmental variables Sicilian calanoid fauna
The eigenvalues for the CCA axes explained al- Sicily, located in the middle of the Mediter-
most the 90o/o of the variance in the species-en- ranean basin, hosts taxa belonging to different
vironment relationship (Table 2). Two distinct chorological zones and represents a natural
tendencies can be observed in Figure 2. One "transition zone" for freshwater taxa (Fig.3), as
et al.
runs horizontally and separates temporary documented by NnsElr-r-FLoRES ( 1998). In
(group C) and permanent (group A and B) wa- particular we highlighted seven chorological
ter bodies. The first group lies on the left part groups, with an equilibrated repartition of the
of the plane and shows a higher species rich- taxa among the chorological categories (Table

Table 2. Summary statistics for the first four axes of CCA.
CCA Axes
E,igenvalues 0.93 0.59 0.3s 0.31
Species-environment correlations 0.91 0.78 0.62 0.59

Cumulative percentage variance
of species data 14.4 23.6 29.0 33.0
- of species-environment relation 3 9 . 1 63.8 78.5 89.5