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Remarkably, Sacchi (1955a, b) arrived to a similar conclusion from analyses of ecological and biogeographical
features. In fact, based on rock boring abilities and morphological similarities between Sicilian Erctella specimens
and the also rupicolous and saxicavous North African Helix subaperta Ancey, 1893, he suggested that the two
groups might have split during the Messinian salinity crisis. In our opinion, even if well-documented land connec-
tions surely occurred, the climatic and ecological conditions during that time made these helicids with very low
active dispersal abilities unlikely candidates for the suggested land-based dispersal process. Hence, we hypothesize
that the separation process between the Sicilian Erctella and similar North African helicids might date back much
further than previously reported, maybe to the Oligocene–Miocene, when the split, dislocation and connection of
microplates of the old Tyrrhenian plate resulted in allopatric speciation events and distribution of vicariant taxa
within the southwestern Mediterranean basin (Giusti & Manganelli 1984; La Greca 1984, 1990a, 1990b; Gueguen
et al. 1998; Rosenbaum et al. 2002; Pfenninger et al. 2010). Nevertheless, further studies of the phylogenetic rela-
tionships between Sicilian and Maghrebinian helicids are certainly needed to address this question, and, maybe,
provide additional support to our speculative hypothesis.

Finally, we express our hope that all findings presented and discussed herein may provide a useful contribution
to the knowledge of these peculiar and extremely vulnerable Sicilian species that will help to organize and manage
adequate conservation measures and habitat protection programs.

Systematics

Helicidae

Erctella Monterosato, 1894

Type species: Helix mazzullii De Cristofori & Jan, 1832, by subsequent designation (Pilsbry 1895: 316).

Shell (Figs. 9–20). Dextral, medium-sized for a helicid (height 24–40 mm, maximum diameter 21–35 mm), glo-
bose-conical, light, uniformly yellowish or brownish, otherwise greenish for the presence of thin periostracum;
sometimes with 3–5 brown spiral bands; external surface with thin growth lines, sometimes particularly wrinkled
and with reticulated appearance; spire more or less elevated with 4–5 convex whorls, last whorl very large; aperture
large, oval to round; sutures deep; umbilicus closed; peristome sharp, sometimes more or less thickened and/or
reflected.

Animal. Yellow, sometimes with mantle border and foot lighter and head slightly darker, or entirely darker
(Benoit 1857; Monterosato 1892).

Genitalia (Figs. 21–23). General scheme of the semidiaulic monotrematic type (incomplete triaulic monotrem-
atic: Visser 1977; Giusti et al. 1995), characterised by diverticulum of bursa copulatrix as long as duct of bursa
copulatrix, or longer; two digitiform glands, each of which is distally divided into 11–45 slender and branched
digit-like appendiges; vagina showing internally smooth and raised opening of free-oviduct, 4–8 small, raised, lon-
gitudinal pleats that disappear near dart-sac opening; a V-shaped pleat around dart-sac opening which continues
with a little pilaster-shaped pleat ending in the genital atrium; penis of medium size, roundish; penial flagellum as
long as penis and epiphallus together, or shorter; distal portion of penis internally divided into proximal and distal
cavities by annular pad; proximal cavity with 14–20 longitudinal pleats, a small papilla on the internal wall and a
very small penial papilla inside opening of proximal penis into distal penis; distal cavity smooth with a raised crest-
like structure situated level with its opening into genital atrium. Inside the genital atrium is a characteristic bulge
which is close to but separate from both the crest-like structure of the distal penis and the small pilaster-shaped
pleat of the vagina.

Remarks. For differences characterizing Erctella with respect to the most closely related genera see Table 6
and the following dichotomous key to the genera Cantareus, Eobania, Cornu and Erctella.

16 · Zootaxa 3134 © 2011 Magnolia Press COLOMBA ET AL.