Page 3 - Guarino_Pasta_2018

rhenian stepping stones could explain the close floristic affinity of the NE Sicilian trachytic
and crystalline siliceous substrata with the corresponding ones of Sardinia, as well as the
occurrence of several W-Mediterranean and Tyrrhenian ancient lineages with remarkable dis-
junctions, currently found as isolated metapopulations or as schizo-endemites in parts of Sici-
ly and/or neighbouring islets which were still submerged during the lower Palaeogene. This
the case, for instance, of Abies nebrodensis, Adenocarpus commutatus and A. bivonii, Ambro-
sina bassii, Bupleurum dianthifolium, Centaurea gr. cineraria, Centaurea gr. parlatoris-deus-
ta, Chamaerops humilis, Convolvulus cneorum, Cytisus aeolicus, Eokochia saxicola, Genista
aetnensis, Genista gr. ephedroides, Glandora rosmarinifolia, Helichrysum gr. panormitanum,
Hyoseris taurina, Oncostema hughii, Pinus calabrica, Pinus pinaster subsp. escarena, Pseu-
doscabiosa limonifolia, Ptilostemon greuteri, Seseli gr. bocconei, Silene gr. mollissima, etc.

The Maghrebid-Apennine range development implied the formation of a complex chain-
foredeep-foreland system. Along with the thrust drift, wide sectors of foreland (like the
Hyblaean Plateau) could have emerged southeastwards already before upper Pliocene. Some
of them may have sunk afterwards. Hence, many species could have colonised the collapsing
emerged areas located at higher latitudes and the rising areas at lower latitudes at stepping sto-
nes or refugia. This could explain the close floristic affinity of the Hyblaean and Maltese pla-
teaus with the carbonatic plateau of Northern Cyrenaica and with the Aegean Region (BRUL-
LO et al. 2011), as well as the occurrence of east-Mediterranean and NE-African ancient
lineages with remarkable disjunctions, currently found as isolated metapopulations or as schi-
zo-endemites in parts of Sicily and/or neighbouring islets which were still submerged during
the lower Palaeogene. This the case, for instance, of Astragalus nebrodensis, A. siculus, A.
kamarinensis, Berberis aetnensis, Bupleurum elatum, Calendula incana s.l., Crucianella
rupestris, Carlina sicula s.l., Desmazeria sicula, Gagea trinervia, Helianthemum sicanorum,
Jurinea bocconii, Muscari gussonei, Onosma canescens, Prangos ferulacea,Prunus prostra-
ta, Retama raetam subsp. gussonei, Siculosciadium nebrodensis, etc.
We intentionally included in the aforementioned list oro- to thermo-Mediterranean species,
which may have reached Sicily by different times, modes and ways, even if the adaptation to
the altomontane conditions, in Sicily, appears to be in most cases the result of a secondary
adaptive radiation of lineages which have now become extinct in the lowlands.
The past occurrence of currently submerged stepping stones may also explain the pre-
sence of many species that spread in the Mediterranean basin during the Messinian sali-
nity crisis and that could not have been surviving in situ on Sicily, given its submersion
until relatively recent times. This is the case of vegetation types to which the following
phytosociological units, currently well represented in Sicily, are referring: Pegano har-
malae-Salsoletea vermiculatae (BRULLO et al. 2012), Saginetea maritimae (BRULLO &
GIUSSO DEL GALDO 2003), Salicornietea fruticosae and Juncetea maritimi (BRULLO
& FURNARI 1976), Rumici-Astragaletea siculi (BRULLO et al. 2005) and the perennial
steppe prairies of Moricandio-Lygeion sparti (BRULLO et al. 2010). All these syntaxa,
related to salty substrata or to mountain debris and talus slopes, are characterized by dis-
continuous distribution patterns throughout the Mediterranean basin and by the abundan-
ce of relict floristic elements (GUARINO 2006, GUARINO at al. 2006).
Fairly all the coastal capes of NW Sicily experienced repeated phases of insularity, as tes-
tified by the so-called fauna of Monte Pellegrino (>1 Ma), hosting an unbalanced fauna with
birds and micromammals of both Eurasian and African origin, and also the following faunistic
assemblages (from 0.95 to 0.1 Ma), characterised by dwarf herbivores (hippopotamuses, ele-
phants, red deers and aurochs), a giant otter, several big carnivores with both African (hyenas)
and Eurasian (bears) origins, etc. (PALOMBO 2018). Egadi islands seem to have shared the

135