Variabilità di Vipera ammodytes (LINNAEUS, 1758) (Reptilia Viperidae) in alcune isole egee, con descrizione di Vipera ammodytes buchholzi subsp. nova.
Naturalista sicil., S. IV, XLV (1-2), 2021, pp. 119-152. DOI:10.5281/zenodo.571346
Summary:
Variability of Vipera ammodytes (Linnaeus, 1758) in several Aegean Islands, with description of a new taxon: Vipera ammodytes buchholzi subsp. nova. The results of a morphological study on 96 specimens of Vipera ammodytes from different Aegean islands, whose populations are usually assigned to the subspecies meridionalis Boulenger, 1903, are given. The Ios population has a faded pattern, triangular rostral with acute apex and tip of the rostral horn consisting of two scales. Iraklia and Naxos populations (northernmost islands) show a stronger coloration, especially on the sides and belly of the ♂♂, hence a more evident sexual dichroism; furthermore the tip of the rostral scale tends to become blunt and the horn to end with a single scale. Specimens from Mykonos stand out for the greater development and definition of the zigzag pattern (especially in the ♀♀, while usually this chromatic element is more evident in the male sex), for the roundy dark spots on the sides and for the peculiar ventral pattern, consisting of dark dots and spots; the rostral scale has often a trapezoidal shape and its apex is placed under the line of the canthus, while the rostral horn culminates in a single apical scale. Population from Tinos has similarities with the southern populations (as the features of the zigzag pattern), but differs from other features, such as the dark ventral coloration, distributed mostly along the free border of the ventral scales as regular and recurring transverse thinbands; lateral spots display features of both the southern populations (vertically elongated shape) and the Mykonos population (rounded shape), even in the same individual; the rostral scale proceeds its south-north trend to become blunt, while the rostral horn ends with 1-4 scales (mostly 2). It should be noted that all the above populations are characterized by small size, probably related to the diet, mainly consisting of small lizards and centipedes; the low number of dorsals, 19 in 20% of the specimens, could be indicative of this trend towards the size reduction. On the contrary, on Paros and Antiparos (where Podarcis lizards are not occurring) vipers are characterized by a more active micro-evolution processes and stand out, among other things, for the low number of ventral scales. In detail, Paros specimens have widespread and marked dark ornamentation which mainly involves the zigzag pattern, the 3-4 lateral rows of spots (rounded) and the belly; on this latter there are thick dots and spots on the distal border of the ventral scales, which can thus appear dark fringed. Even the dorsal background color seems to comply with this condition of higher intensity of dark pigments. They also differ in the slightly marked eyebrow margin, in the low number of ventral scales and in the relatively high number of subcaudals. The rostral scale is generally as isosceles triangle-shaped, and the tip of the rostral horn consisting of 2 scales. The Antiparos population is morphologically very close to that of Paros, at least as regards the males; in this sex the ornamentation is well-established, both dorsally (up to four rows of dark spots along the sides, well-marked and increasingly rounded ventral-dorsally) and ventrally (with scattered dark dots and spots arranged on the distal border of the ventral scales, sometimes joined to mark the scales). Females appear instead light, tending to a yellow-ocher background with a very faded pattern. The low number of ventral scales and the relatively high number of subcaudals scales are discriminating factors. The rostral scale is sub-triangularly shaped with a more or less blunt tip that often reaches the canthus and with above a horn generally ending with 1-3 apical scales. Both Paros and Antiparos populations are hence assigned to a new taxon, Vipera ammodytes buchholzi ssp. nov. Finally, in the Northern Sporades, Vipera ammodytes is larger and shows a particular pholidosis that makes it close to the conspecific populations of central-northern Greece.
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