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A Leucistic Grass Snake Natrix Natrix (Linnaeus, 1758) (Serpentes: Natricidae) from Tuscany, Central Italy

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A Leucistic Grass Snake Natrix Natrix (Linnaeus, 1758) (Serpentes: Natricidae) from Tuscany, Central Italy Herpetology Notes, volume 10: 313-316 (2017) (published online on 30 May 2017) A leucistic grass snake Natrix natrix (Linnaeus, 1758) (Serpentes: Natricidae) from Tuscany, Central Italy Giacomo Bruni* Snakes species evolved different colouration patterns thermoregulatory efficiency, leucistic snakes lack of in response to selective pressure enhancing functions camouflage and this means that they are easily detected such as thermoregulation, camouflage, warning and by prey and predators, with harmful consequences on mimicry (Bechtel, 1978; Krecsák, 2008). Additionally, their survival rate and fitness (Krecsák, 2008). a variety of chromatic anomalies have been reported in The grass snake (Natrix natrix) is a species associated snakes, of which the most frequently observed in the with freshwater habitats and preys mainly on amphibians. wild are melanism, leucism and albinism (Krecsák, It is widely distributed, from France to Central Asia, 2008; Castella et al., 2013). Melanism is rather including Great Britain, Ireland, Scandinavia, the common in snakes and refers to completely or almost Italian peninsula, Sicily, Sardinia, Balkans and the totally black individuals Zuffi, 2008). 7he presencH0iddle East (Beebe and Griffiths, 2000; Sindaco et al., of leucism is recognised when snakes show a low 2013, Pokrant et al., 2016). In Italy, the species can be number of iridophores, and few or no melanophores and found from sea level to 2300 m a.s.l. (Scali et al., 2011). xanthophores (Bechtel, 1991). Entirely leucistic snakes Although the taxonomic classification of N. natrix are therefore characterized by an all-white colouration in Italy remains subject to debate, presence of three and pigmented eyes, usually black or blue (Wareham, subspecies has been confirmed by molecular studies 2005). In comparison, snakes affected by albinism (Fritz et al., 2012; Kindler et al., 2013): N. n. sicula display red eyes and a yellowish or pinkish colouring (Cuvier, 1829) in Sicily and in the southern part of due to the presence of xanthophores and eritrophores, Calabria, N. n. cetti (Gené, 1838) in Sardinia and N. n. usually in combination with visible patterns (e. g. helvetica (Lacépède, 1789) along the Italian peninsula Silvestre et al., 2009; Silva et al., 2010; Abegg et al., from the Alps to Calabria. Several cases of chromatic 2015). In nature, leucistic snakes are rare and less aberration have been reported for N. natrix, in particular common than albino snakes (Krecsák, 2008). A possible concerning melanistic individuals (e.g. Bruno, 1970; explanation is that the lack or absence of melanophores Jandzík, 2004; Gvozdenović and Schweiger, 2014), and xanthophores means that these snakes are unable to while few reports concern albinos (e.g. Procter, 1926; thermoregulate properly (Kornilios, 2014). In snakes, a Kabish, 1974; Bruno, 1984). No clear cases have weak thermoregulatory efficiency has a negative impact currently been reported involving leucistic individuals. on locomotion and digestion (Stevenson et al., 1985). Nevertheless, De Betta (1863) reported a putative case It is well-known that dark colour in snakes leads to a of leucism in the environs of Pavia, northern Italy; he greater efficiency in thermoregulation compared to briefly described a young specimen with a uniformly white individuals (Gibson and Falls, 1979). Moreover, whitish colour without any marks, but unfortunately no melanin defends internal organs from damaging effects details about the eye colouring were reported. of solar radiation (Bechtel, 1978). In addition to reduced 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 Vrije Universiteit Brussel, Boulevard de la Plaine 2, 1050 180 m a.s.l., along the Zambra stream valley in the Ixelles, Bruxelles, Belgium. Municipality of Sesto Fiorentino, in the Province of Corresponding author e-mail: [email protected] Florence. The individual was crawling actively along a 314 Giacomo Bruni Figure 1. Leucistic male of Natrix natrix observed on Monte Morello (Tuscany); brown colouration is irregularly present due to mud on the skin. (A) Dorsal view; (B) Left side of the head with one postnasal scale; (C) Right side of the head with two postnasal scales; (D) Pink coloured tongue. path at the edge of the wood, not far from the dry stream Even though it is a common species with a wide bed. The sighting was documented in situ using a Nikon distribution, the discovery of leucistic individuals of D7000 digital SLR camera. The snake colour was totally N. natrix seems extremely rare, with no cases clearly white in both dorsal and ventral side without any marks documented. The observation reported here appears related to the typical pattern, while only on the head even more remarkable since the individual is not a small greyish nuanced areas occurred. The eyes were new-born snake. As mentioned before, the risk of being black, with a silvery iris including blue shades, while the predated appears to be higher for leucistic individuals, pupil consisted of very dark red colour. The tongue was which seems to be confirmed by the presence of pink. The tail appeared recently severed with unhealed scars on the body and by the wound on the tail in the wound, while also on the dorsal side of the body some observed individual. The white colouring, in addition small scars were present. The individual was measured to making the snake more detectable, reflects the using a tape measure. Pholidosis characteristics were incident radiation reducing the absorption of thermal taken as reported in Scali et al. (2011). The leucistic energy. Therefore, in view of its slow heating level male had a total length of 600 mm and the remaining and poor thermoregulatory efficiency, a snake affected part of the tail was 80 mm long. These measures may be by leucism requires more time to obtain the necessary underestimated because the snake was measured without body temperature to be active (Kreczak, 2008), and physically stretching it. Regarding the pholidosis, the to implement digestive processes (Skoczylas, 1970). individual presented 19 dorsal and 172 ventral scales, Consequently, longer thermoregulatory time implies a seven upper labial and 11 lower labial scales, three major exposure to potential predators. Vice versa, the postocular and one preocular scales. The number of predatory success of the leucistic snake could be marred scales falls into the known range for the species (Lanza, by the absence of camouflage. As assumed by Kreczak 1983). An anomaly occurs in the postnasal scale on the (2008), it is possible that survived leucistic individuals right side which is divided into two distinct scales. thermoregulate partially hidden, by adopting a trade-off A leucistic grass snake Natrix natrix from Tuscany, Central Italy 315 between exposure and protection. Because N. natrix delineation of grass snakes. Organisms, Diversity & Evolution throughout its southern distribution can be found in 12: 71–80. water during the night, in particular in stagnant water Gibson, A.R., Falls, B.B. (1979): Thermal biology of the common garter snake Thamnophis sirtalis (L.). Oecologia, 43(1): 79–97. (pers. obs.; see also Capula et al., 1994) where the Gvozdenović, S., Schweiger, M. (2014): Melanism in Natrix natrix temperature is maintained higher compared to that and Natrix tessellata (Serpentes: Colubridae) from Montenegro. of the air, it is possible that this leucistic snake could Ecologica Montenegrina 1(4): 231–233. survive so long thanks to overnight activity. Given that Jandzík, D. (2004): Partial melanism in the grass snake Natrix the expression of rare alleles (e.g. leucism) occurs more natrix (Reptilia: Colubridae) from northeastern Slovakia. Acta frequently in small and fragmented populations due to Zoologica Universitatis Comenianae 46(2): 75–77. the loss of genetic variability (Laikre, 1999), and that Kabisch, K. (1974): Die Ringelnatter: Natrix natrix (L.). Ziemsen. Kindler, C., Böhme, W., Corti, C., Gvoždík, V., Jablonski, D., the area where the individual was found changed in Jandzik, D., Metallinou, M., Široký, P., Fritz, U. (2013): the early 2000s due to human impact (e.g. Rodolfi et Mitochondrial phylogeography, contact zones and taxonomy al., 2004), a future study to evaluate the frequency of of grass snakes (Natrix natrix, N. megalocephala). =oologica leucism in the population could be interesting. Scripta 42(5): 458–472. Kornilios, P. (2014): First report of piebaldism in scolecophidians: Acknowledgements. I wish to thank Dario Domeneghetti for a case of Typhlops vermicularis (Squamata: Typhlopidae). his help with relevant advice and for the implementation of the Herpetology Notes 7: 401–403. pictures collage. Luca Cavigioli, Francesco Paolo Faraone and Krecsák, L. (2008): Albinism and leucism among European Grégoire Meier for their useful suggestions. Marco A. L. Zuffi Viperinae: a review. Russian Journal of Herpetology 15(2): for reading the draft of the manuscript and for improving it with 97–102. his criticism. Richard Joseph Cooper for helping to improve the Laikre, L. (1999): Hereditary defects and conservation genetic English of the manuscript. management of captive populations. Zoo Biology 18: 81–99. Lanza, B. (1983): Guide per il riconoscimento delle specie animali delle acque interne italiane. 27. Anfibi, Rettili (Amphibia, References Reptilia). Collana del Progetto Finalizzato «Promozione della Abegg, A.D., Entiauspe-Neto, O.M., de Lema, T. (2015): First Qualità dell’Ambiente» AQ/1/205. Consiglio Nazionale delle record of albinism in the Elapomorphini tribe (Serpentes: Ricerche, Roma. Dipsadidae). Herpetology Notes 8: 503–505. Pokrant, F., Kindler, C., Ivanov, M., Cheylan, M., Geniez, P., Beebe, T., Griffiths, R. (2000): Amphibians and Reptiles: A Natural Böhme, W., Fritz, U. (2016): Integrative taxonomy provides History of the British Herpetofauna. Harper Collins, London. evidence for the species status of the Ibero-Maghrebian grass Bechtel, H.B. (1978): Color and pattern in snakes (Reptilia, snake Natrix astreptophora.
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