Podarcis siculus (Reptilia: Sauria: Lacertidae), a new alien species for Russian fauna

Abstract

Podarcis siculus (Rafinesque-Schmaltz, 1810) or Italian wall lizard is one of the most invasive reptile-species. Recently, this lacertid lizard has been introduced to Mediterranean areas of southern Europe, South-West Asia (Turkey) and North America (USA). An abundant population of P. siculus was discovered on one of the sites of the Natural Ornithological Park in the Imeretinskaya Lowland, on an area of over 0.22 km2 (Sochi, Russia). The data were collected in the May of 2020 in a strip survey method in the Imeretinskaya Lowland. To identify the colonization area of the invader, we examined all 8 sections of the Natural Ornithological Park in the Imeretinskaya Lowland and adjacent urbanized areas. More than 150 animals were observed. These Italian wall lizards, undoubtedly, belong to the northern-central Italian morphotype (presumably P. s. campestris). This is the first record of this species in the former USSR area and, also, this is the species’ north-easternmost locality. The population inhabits secondary natural biotopes and urban area. Among them are the banks of artificial water bodies, areas with cultivated trees and shrubs, as well as parks, and house lawns in the urban area. Population density was estimated from eight to 40 specimens per 100 m of the transect. A moderate proportion of young specimens (more than a 40%) would indicate a healthy and continued growth of the emerging population. To determine the possible period of the species introduction, space images of the Imeretinskaya Lowland were analyzed beginning from the transformation of its landscape for the Winter Olympic Games of Sochi 2014 until the May of 2020. The introduction of the species presumably occurred with the delivery of large-sized ornamental trees and shrubs from Italy in 2012–2013. Podarcis siculus should be included in the list of herpetofauna of Russia and particularly of the Caucasus. This is an alien species with a proven ability to become an invasive species, what will lead to a greater undesirable and unavoidable contact with native small lizards of the genus Darevskia Arribas, 1997. On the other hand, as it is often observed with new invaders, a sudden rise in population abundance could be followed by a sharp decline. A continuous monitoring of the area in question and of the number of local Italian wall lizards is necessary to confirm or refute the assumed scenarios of further invasion of P. siculus on the Black Sea Coast of the Caucasus. Further action plans for this population should be developed depending on supposed future trends.