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same destiny, as testified by their endemic element, which shows a remarkable floristic affi-
nity with the promontories of Western Sicily (Asperula rupestris, Asplenium petrarchae, Cen-
taurea ucriae and C. umbrosa, Euphorbia papillaris, Glandora rosmarinifolia, Iberis semper-
florens, Pseudoscabiosa limonifolia, Seseli bocconii, Simethis mattiazzi, etc.).
Within the framework outlined, some open questions remain concerning palaeoendemites
whose distribution pattern remains unexplained. A remarkable example is provided by Urtica
rupestris, endemic to the Hyblaean canyons and similar to Urtica morifolia of the Canary
Islands (BARTOLO et al. 1998), which has no other allied relict population in the W-Mediter-
ranean basin. A similar case concerns Cistus clusii, a west Mediterranean species reaching in
the Hyblaean plateau and Apulia the most eastern and disjunct outposts of its distribution
range (BRULLO et al. 2011). On the other hand, it is difficult to explain how Erica sicula, the
only representative of the section Pentapera in the flora of Italy, managed to reach the recently
emerged cliffs of some NW coastal capes of Sicily, being its closest relatives currently scat-
tered in Cyrenaica, Lebanon, Anatolia and Cyprus (FAGÚNDEZ & IZCO 2011).
Another unsolved enigma concerns the occurrence of Cytisus aeolicus, an arborescent
broom endemic to Aeolian Islands with no near relatives in the whole Euro-Mediterranean.
Taking into consideration its evolutionary isolation (see TROÌA 2012 and references therein),
it has to be considered far more ancient than the Aeolian Archipelago itself, whose volcanoes
started to emerge less than one million years ago. Similarly, no one knows how Genista aet-
nensis, another ancient and taxonomically isolated species, managed to reach the much youn-
ger slopes of Mt. Etna, being the nearest wild populations in Eastern Sardinia.

Fig. 1: Map with isobaths and name of satellite islands (after: PASTA & LA MANTIA 2013, modified)

The species belonging to the only two monotypic endemic Sicilian genera, i.e. Petagnaea
gussonei and Siculosciadum nebrodensis, only occur at the boundary between Peloritani and
Nebrodi Mts. the former and on Madonie Mts. the latter. Considering that their nearest rela-

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