A leucistic grass snake Natrix natrix (Linnaeus, 1758) (Serpentes: Natricidae) from Tuscany, Central Italy

in response to selective pressure enhancing functions such as thermoregulation, camouflage, warning and mimicry (Bechtel, 1978; Krecsák, 2008). Additionally, a variety of chromatic anomalies have been reported in snakes, of which the most frequently observed in the wild are melanism, leucism and albinism (Krecsák, 2008; Castella et al., 2013). Melanism is rather common in snakes and refers to completely or almost totally black individuals Zuffi, 2008). he presenc of leucism is recognised when snakes show a low number of iridophores, and few or no melanophores and xanthophores (Bechtel, 1991). Entirely leucistic snakes are therefore characterized by an all-white colouration and pigmented eyes, usually black or blue (Wareham, 2005). In comparison, snakes affected by albinism display red eyes and a yellowish or pinkish colouring due to the presence of xanthophores and eritrophores, usually in combination with visible patterns (e. g. Silvestre et al., 2009; Silva et al., 2010; Abegg et al., 2015). In nature, leucistic snakes are rare and less common than albino snakes (Krecsák, 2008). A possible explanation is that the lack or absence of melanophores and xanthophores means that these snakes are unable to thermoregulate properly (Kornilios, 2014). In snakes, a weak thermoregulatory efficiency has a negative impact on locomotion and digestion (Stevenson et al., 1985). It is well-known that dark colour in snakes leads to a greater efficiency in thermoregulation compared to white individuals (Gibson and Falls, 1979). Moreover, melanin defends internal organs from damaging effects of solar radiation (Bechtel, 1978). In addition to reduced thermoregulatory efficiency, leucistic snakes lack of camouflage and this means that they are easily detected by prey and predators, with harmful consequences on their survival rate and fitness (Krecsák, 2008). The grass snake (Natrix natrix) is a species associated with freshwater habitats and preys mainly on amphibians. It is widely distributed, from France to Central Asia, including Great Britain, Ireland, Scandinavia, the Italian peninsula, Sicily, Sardinia, Balkans and the iddle East (Beebe and Griffiths, 2000; Sindaco et al., 2013, Pokrant et al., 2016). In Italy, the species can be found from sea level to 2300 m a.s. l. (Scali et al., 2011). Although the taxonomic classification of N. natrix in Italy remains subject to debate, presence of three subspecies has been confirmed by molecular studies (Fritz et al., 2012; Kindler et al., 2013): N. n. sicula (Cuvier, 1829) in Sicily and in the southern part of Calabria, N. n. cetti (Gené, 1838) in Sardinia and N. n. helvetica (Lacépède, 1789) along the Italian peninsula from the Alps to Calabria. Several cases of chromatic aberration have been reported for N. natrix, in particular concerning melanistic individuals (e.g. Bruno, 1970; Jandzík, 2004; Gvozdenović and Schweiger, 2014), while few reports concern albinos (e.g. Procter, 1926; Kabish, 1974; Bruno, 1984). No clear cases have currently been reported involving leucistic individuals. Nevertheless, De Betta (1863) reported a putative case of leucism in the environs of Pavia, northern Italy; he briefly described a young specimen with a uniformly whitish colour without any marks, but unfortunately no details about the eye colouring were reported. Herein, I report on the discovery of a leucistic male of N. natrix in Tuscany, providing photographic documentation and details about the pholidosis. On 26/05/2015 at 10:35 a.m. I found a white male of N. natrix on the south slope of the Monte Morello at 180 m a.s. l. , along the Zambra stream valley in the Municipality of Sesto Fiorentino, in the Province of Florence. The individual was crawling actively along a Herpetology Notes, volume 10: 313-316 (2017) (published online on 30 May 2017)