Pond frog ( lessonae) – a kind of real frogs.DescriptionThe body length of the pond frog rarely exceeds 8 cm.The coloration of the dorsal side is usually bright green, gray-green, olive or brown, with more or less dark spots; a narrow light longitudinal stripe often runs along the middle of the back, the ventral side is uniformly white or yellowish. Some individuals lack a back pattern and have small spots on the throat or front of the belly. The eardrums are well developed. There are often stripes on the sides of the head that run from the tip of the muzzle through the nostrils, eyes, and sometimes the eardrums. On the lower part of the foot there is a high and laterally compressed calcaneal tubercle, there are swimming membranes. In males, on the first two or three inner fingers of the forelimbs, dark brown nuptial calluses are developed, and on the sides of the head in the corners of the mouth there is a pair of external sound resonators of white color. During the breeding season, the trunk of males can be yellowish.The pond frog differs from the edible frog by a larger internal calcaneal tubercle and relatively limbs, if the legs are pressed against the hips and placed on both legs perpendicular to the longitudinal axis of the body, then the ankle joints do not touch and do not go over each other.Habitat and habitatsThe pond frog is widespread in central Europe, from western France to the Volga region in the east (it moves to the left bank of the Volga in its middle reaches). The northern border of the range passes through Holland, southern Sweden and further through the north-west of Russia (Leningrad and Novgorod regions), Bashkiria and Tatarstan. In the south, the coincides with the forest and forest-steppe zone and is limited to the north of Italy, the northern foothills of the Alps and the Balkans, northern Romania, and the central-southern regions of Ukraine. Historical records, museum pieces and modern zoogeographic research suggest that the pond frog is an aboriginal and not an introduced species in England. Introduced in southern Norway.In its pure form (without admixture of lake and edible frogs) in Eastern Europe, it is reliably known only from some areas of the Moscow and Leningrad regions.Inhabits low-flowing or stagnant shallow water bodies of and mixed forests, meeting after breeding in moist forests and far from water. In forest-steppe and steppes, it lives only in water bodies, mainly in oxbows of rivers and ponds. The acidity of such reservoirs ranges from pH = 5.8-7.4. In the mountains rises to a height of 1550 m.OriginCurrently, the pond frog is considered a monotypic species.[прояснить] Judging by the data of an immunological study, its separation from a common ancestor with a marsh frog took place about 12 million years ago. In Ukraine, it is known from the Lower Pleistocene – Holocene of the middle reaches of the Dnieper.