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● Poggio Schinaldo (Cinisi, Palermo), from the Elephas falconeri complex in cave deposit (Esu et al. 1986).

The shell of the sample from Alcamo is globose, weakly cancellated and rugose, and hence completely differ-
ent from H. luparellensis. This evidence suggests that during the Middle Pleistocene at least three different shell
morphotypes (H. mazzullii from Monte Pellegrino, H. cf. mazzullii from Alcamo and Poggio Schinaldo, H. luparel-
lensis from Baida) belonging to the H. mazzullii group occurred in the Palermo area.

Fossil shells of H. cephalaeditana have been observed in the talus slope of La Rocca of Cefalù (personal data).
Notably, these specimens are much bigger (height 40 mm; maximum diameter 38 mm) than shells of modern spec-
imens (Fig. 34).

Several paleontological reports of fossils of H. mazzullii attributable to the taxon insolida include:

● Grotta di Caciucavaddu (Levanzo, Egadi Islands, Trapani), quaternary deposits (De Gregorio 1927; Fiorentino
et al. 2004)

● Monte San Giuliano (Trapani), quaternary rock (De Gregorio 1927)
● coastal zone of Cala Mancina (south-west of San Vito lo Capo, Trapani), near Grotta dei Cavalli, breccias (per-

sonal data) (Fig. 35)
● Favignana (Egadi Islands, Trapani) (Fig. 36), Lower Pleistocene, (personal data)
● Grotta dell’Uzzo, meso-neolithic (10–8.3 thousand years ago) (Compagnoni 1993; Piperno 1997).

Discussion

This study represents the first comprehensive analysis of the H. mazzullii group from Sicily, one of the most inter-
esting, yet least well-known Helicidae taxa. Data discussed herein confirm the existence of a certain degree of dif-
ferentiation within the group, as already suggested by many authors on the grounds of shell morphology (Figs. 37–
41) and genital features (Pirajno 1840; Benoit 1857; Monterosato 1892; 1894; Pilsbry 1895; Hesse 1919; Cockerell
1921; Giannuzzi-Savelli et al. 1986; Falconieri 1995; Colomba et al. 2008; Ryolo & Palazzi 2009; Liberto et al.
2010).

The presence of fossil shells of mazzullii s.l. specimens is well documented in many continental deposits of
Sicily, which suggests that the group might have occurred at least in the late Pliocene–early Pleistocene (Montero-
sato 1872, 1877, 1891; De Gregorio 1886, 1895, 1899, 1916a, 1916b, 1927; Kotsakis 1979; Belluomini & Bada
1985; Esu et al. 1986; Burgio & Cani 1988; Bada et al. 1991; Bonfiglio & Burgio 1992; Burgio 1998; Fiorentino et
al. 2004; Abate et al. 2006; personal data). Nevertheless, although these records indicate the terminus after which
the mazzullii group certainly occurred, we cannot rule out the possibility of an earlier appearance. In fact, our
BEAST analyses suggest that the origin of the mazzullii group can be dated about 10.7±0.07 million years ago and
that the split of the sister taxa mazzullii and cephalaeditana likely occurred about 8.98±0.07 million years ago.
Moreover, the BEAST and MEGA time estimates are largely congruent. With MEGA, node ages were dated to
about 8.82 (origin of the mazzullii group) and 7.9 (divergence between mazzullii and cephalaeditana) million years
ago. Hence our results indicate that both dichotomic events might have taken place long before the Messinian salin-
ity crisis, suggesting a longer evolutionary history for the mazzullii group than expected. This agrees with the
occurrence of a peculiar H. mazzullii-associated vertebrate fauna known as Pellegrinia fauna (after Pellegrinia
panormensis, an endemic genus and species of the African family Ctenodactylidae [Mammalia, Rodentia] [De
Gregorio, 1886] which may be a survivor of Oligocene–early Miocene faunas [Azzaroli & Guascone 1979;
Azzaroli 1990]), in one of the oldest continental fossil deposits of Sicily (Monte Pellegrino).

Considering the specimen sampling which covered representative sites throughout the distribution area of the
group and the robust phylogenetic reconstruction based on nucleotide patterns of two mitochondrial (16S and 12S
rDNA) and one nuclear (ITS-2) gene fragments, we propose the following system: the mazzullii group consists of
three species, insolida, mazzullii and cephalaeditana, with a sister relationship for the latter two.

Remarkably, intraspecific mtDNA sequence divergences observed within the mazzullii group (1.3% for 16S
rDNA; 1.6% for 12S rDNA) are much lower than those reported for other land snails (up to 12.9%, see, e.g.,
Thomaz et al. 1996; Hayashi & Chiba 2000; Watanabe & Chiba 2001), and the mutation rate (0.48% per million
years for both 16S rDNA and 12S rDNA) is not high. This might indicate that an accelerated mtDNA evolution

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