Ermakov O. A. RussiaPenzaPenza State University, 40 Krasnaya Str., Penza 440026, Russiaoaermakov@list.ru Author's articles DISTRIBUTION OF THE «EASTERN» AND «WESTERN» FORMS OF THE MARSH FROG, PELOPHYLAX RIDIBUNDUS, AND THEIR PARTICIPATION IN THE ORIGIN OF HEMICLONAL HYBRIDS, P. ESCULENTUS IN MARI EL REPUBLIC