Podarcis sicula is a small to medium sized lizard, ranging from 5½ to 9½ in (14 to 24 cm) TL, with a max SVL of 3½ in (9 cm). Dorsal coloration ranges from gray and tan to green; ventral coloration is a pure white or gray. Dark reticulations are often present mid-dorsally and laterally. A thin yellowish band often boarders each margin of the lateral reticulations. Dorsal scales are fine and granular, while ventral scales are large and rectangular, and arranged in longitudinal rows. A complete gular fold is present. Noticable femoral pores are present. One single pre-anal scale is present. Male. The male is easily distinguished by the swollen base of the tail, caused by the presence of hemepenes, enlarged femoral pores, and the presence of a blue spot dorsal to the forelimb. Female. Females lack the enlarged base of the tail and femoral pores, and have a green spot dorsal to the forelimb, instead of blue. Hatchling. Hatchlings are minute lizards, with a SVL of ~½ in (1.2 cm), and are generally tan in overall body color.
The Six-lined Racerunner (Aspidoscelis sexlineata) may be confused with Podarcis sicula due to the similarity of body form and green color. Podarcis sicula can be differentiated from all species of Aspidoscelis, including A. sexlineata, by the presence of only a single pre-anal scale.
Podarcis sicula is native to Bosnia and Herzegovina, Croatia, France, Italy, Montenegro, Slovenia, and Switzerland. Populations have been introduced in Spain, Turkey, and the United States. In the United States there are populations located in West Hempstead and Garden City, Long Island, New York; Hays, Lawrence, and Topeka, Kansas, and, at least formally, Philadelphia, Pennsylvania.
Found natively in costal habitats, riparian areas, grassy fields, forest edges, farmland, stone walls, ruins, the sides of buildings, and other urban environments. In the United States, populations are restricted to urban areas and dwell in rubble, around buildings, and other such habitat that provides suitable areas for basking and shelter. Individuals at Fort Hays State University in Kansas utilize cracks in building foundations as hibernacula.
Microhabitat selection at Fort Hays State University include sidewalks (especially those with large cracks that have been subsequently sealed, as these seals provide shelter once they begin to pull away from the concrete), sides of buildings, planters and garden areas, and even statuary. Individuals often use Juniperus spp. as basking sites during warmer months. Apparently olfactory cues are important in microhabitat selection, as individuals from the native range exhibit strong reactions to the scent of a lizard eating snake, and will actively avoid microhabitats where the olfactory cues from the snake are present.
Lizard emergence from hibernation at Fort Hays State University occurs in March and April with an end to daily activity occurring in late October or early November, although lizards have been observed in December through February basking in secluded, south-facing areas with on some buildings on clear, windless days. The lowest air temperature at which lizards were seen basking was 22°F (-5.5°C) on a sunny January day. Undoubtedly, the secluded basking sites attain a much higher temperature. In Italy, body temperatures of active individuals ranged from 72 to 101°F (22.4 to 38.5°C), with lower average body temperatures in the early spring and late fall versus higher average body temperatures from late spring through early fall.) Podarcis sicula shows low tolerance to freezing, and surprisingly short durations exposed to freezing temperatures are lethal. This may explain why these lizards have failed to colonize outside of urban areas, as access to heat retained by buildings may be an important survival strategy. During the early spring, activity patterns are distinctly unimodal. Daily activity becomes bimodal (morning and evening) as the season progresses, and becomes unimodal again in the autumn. This has been shown to be a programmed circadian rhythm in response to changing seasons instead of a response to changing temperatures.. On any given day, only a percentage of individuals are active.
Reproduction and growth
Breeding likely takes place in the spring. Eggs are likely deposited in early summer. Hatchlings begin emerging in late July. Individuals mature after their second winter. Average life span is 4-5 years in the wild. Populations at Fort Hays State University are fairly dense; the estimated population on the central quad (about 19 acres) is well over 3,000 individuals.
This species eats mainly invertebrates, such as insects (orthopterans, coleopterans, dipterans, lepidopterans) and spiders. An introduced population on an island in the Adriatic Sea has rapidly evolved in the 39 years it has been present to include a large amount of vegetation in its diet. As a consequence, the skull has become broader and is capable of a more powerful bite force. In addition, the intestinal tract has been modified to include cecal valves, which create chambers in the intestine that facilitate microscopic organismal growth, which in turn help digest the cellulose in the plant matter. These valves are similar to those in other vegetarian lizards, but are a novel development for Podarcis, and in fact are present in less than 1% of all known squamates.
Taxonomy and variation
There are 6 recognized subspecies, forming 2 distinct clades, although the genetic standing of introduced populations is unclear. This species has populations that are rapidly evolving (see Herrel, et al).
Recently, the gender of the genus Podarcis was determined to be masculine, which changes the specific epitaph of this species from sicula to siculus under the rules of the ICZN.
- Conant, R and J. T. Collins. 1991. Reptiles and amphibians of eastern and central North America. Houghton Mifflin Co., Boston.
- Powell, R, J. T. Collins, and E. D. Hooper, Jr. 1998. A key to amphibians and reptiles of the continental United States and Canada. The University Press of Kansas.
- Isailovic, J.C., Vogrin, M., Corti, C., Mellado, V.P., Sá-Sousa, P., Cheylan, M. & Pleguezuelos, J. 2005. Podarcis sicula. The IUCN Red List of Threatened Species. Accessed on 21 August 2010.
- Burke, R. L., A. A. Hussain, J. M. Storey, and K. B. Storey. 2002. Freeze tolerance and supercooling ability in the Italian Wall Lizard, Podarcis sicula, introduced to Long Island, New York. Copeia, 2002(3), pp. 836–842.
- Taggart, Travis W. Italian Wall Lizard. Kansas Herpetofaunal Atlas. Accessed 21 August, 2010.
- Ryan Shofner, pers. obs.
- Van Damme, R., and K. Quick. 2001. Use of Predator Chemical Cues by Three Species of Lacertid Lizards (Lacerta bedriagae, Podarcis tiliguerta, and Podarcis sicula). Journal of Herpetology, Vol. 35, No. 1, pp. 27-36
- Tosini, G., A. Foa, and R. A. Avery. 1992. Body temperatures and exposure to sunshine of ruin lizards Podarcis sicula in central Italy. Amphibia-Reptilia, Vo. 13, No. 2, pp. 169-175(7
- Bill Stark, PhD, pers. com. with Ryan Shofner
- Foà, A., G. Mouteforti, L. Minutini, A. Innocenti, C. Quaglieri, and M. Flamini. 1994. Seasonal changes of locomotor activity patterns in ruin lizards Podarcis sicula. Behavioral Ecology and Sociobiology, Vol. 34, No. 4, pp. 267-274.
- Herrel, A., K. Huyghe, B. Vanhooydonck, T. Backeljau, K. Breugelmans, I. Grbac, R. Van Damme, and D. J. Irschick. 2008. Rapid large-scale evolutionary divergence in morphology and performance associated with exploitation of a different dietary resource. Proceedings of the National Academy of Science U S A., 105(12): 4792–4795.
- Podnar, M., W. Mayer, and N. Tvrtković. 2005. Phylogeography of the Italian wall lizard, Podarcis sicula, as revealed by mitochondrial DNA sequences. Molecular Ecology Vo. 14, Is. 2, pp. 575–588.
- Böhme, W. and J. Köhler. 2004. Do endings of adjective flexible species names affect stability? A final note on the gender of Podarcis Wagler, 1830 (Reptilia, Lacertidae). Bonner Zoologische Beitrage. 53: pp. 293-295.
Podarcis - Wall Lizards
- Podarcis sicula - Italian Wall Lizard