In some scientific papers on amphibian helmintofauna the species of trematode Prosotocus confusus Looss, 1894 was identified as the Prosotocus fuelleborni (Travassos, 1930), Distomum (Brachycoelium) clavigerum Dujardin, 1845; Distomum confusum Looss 1894; Distomum clavigerum Pagenst., 1897; Prosotocus confusus Looss, 1899 Pleurogenes confusus Klein, 1905 (Rijicova et al., 1980). In the central zone of Codri in Republic of Moldova the species Prosotocus confusus was found in the small intestine and stomach of the amphibian from the complex Pelophylax esculenta (Amphibia), although some researchers identified this species only in the small intestine in the amphibians from the complex Pelophylax esculenta and other species, such as R.terrestris, R. temporaria, Bombina bombina, Pelobates toad, Bufo viridis, B. bufo, B. calamita (Rijicova et al., 1980). Description of species Prosotocus confusus Looss, 1894 in this scientific paper is based on the study of 865 specimens obtained from Rana ridibunda, R. lessonae and R.esculenta species caught from four natural basins of and eight anthropogenic basins (Figure 1). Morphologically, the body can be circular, elliptical, ovoid, pear-shaped with a length of 0.396-0.804 mm and a width of 0.295-0.638 mm. Thorns covers the entire body except the rear end, being more dense in the first half of the body. Oral sucker with the diameter of 0.091- 0.084 x 0.153 -0.168 mm is terminal or rarely subterminal and ventral sucker of 0.087-0.091 x 0.177-0.168 mm in diameter is in postcaudal region of the body. Left intestinal branch, as length is shorter than intestinal right branch. Excretory bladder branches reach up to the ventral sucker. The testicles are oval or irregularly shaped, diameter is 0.093-0.084 x 0.093-0.079 mm, situated at the glottis or intestinal bifurcation. Copulatory organ, in appearance of bludgeon, is typically positioned along the left side of the body, rarely - obliquely touching the bottom or middle of the ventral sucker. Genital pore is marginal or submarginal, located in the esophagus or intestinal bifurcation, behind the left testicle, preacetabular. Ovary diameter of 0.042-0.034 x 0.131-0.171 mm is located medial or submedial at the genital pore, preacetabular. Vitelogene glands are located in the first half of the body above the testicles, from the oral sucker to the level of the bifurcation of the testes or intestine. The ootype comes from the uterus to the left, then turn toward the rear of the body and behind the ventral sucker goes to the right side of the body forming loops aimed at atrium. The metraterm is not big, usually has the appearance of the letter S. The eggs have a diameter of 0.011-0.070 x 0.018-0.012 mm (Table 1). Biological cycle. Trematoda Prosotocus confusus Looss, 1894 is registered frequently in Anuran amphibians - the definitive hosts. The first intermediate host is the mollusk Bithynia Leach. In this mollusk the miracidium forms sporocysts, containing 4-8 cercariae. The second intermediate hosts are larvae of dragonflies - Sympetrum flaveolum, S. berth, Aeschna isosceles, A. viridis, A.granda, Coenagrion puella larvae of trichopterans Phryganea grandis, Agrypnia sp., and imago larvae of beetles Hydrous piceus, C. laterimarginalis, crustaceans and ephemeral. The metacercariae of this parasite are predisposed to progenesis (larval multiplication). Trematode Prosotocus confusus in some cases has been established in field lizards Lacerta agilis Linnaeus, 1758 and snake Natrix natrix Linnaeus, 1758 - as optional hosts (Rijicova et al., 1980). Aknowledgement: The work was performed within the project 15.817.02.12F financed by Academy of Sciences of Moldova.