Marine parasite in a freshwater wetland: new host and geographical records of (Cestoda: Trypanorhyncha) from (Actinopterygii: Gasterosteidae) in Bulgaria, with comments on its life-cycle.

Plerocerci of the trypanorhynch cestode Beveridge, Neifar & Euzet, (Progrillotiidae) were isolated from the gallbladder of the three-spined stickleback from a small freshwater marsh in the Lake Atanasovsko Wetlands, a coastal area adjacent to the Black Sea coast, Bulgaria. The parasite was recorded in five out of 134 fish individuals studied (prevalence 3.73%, intensity 1-7, mean intensity 2.40 ± 1.17 and mean abundance 0.09 ± 0.06). A description of the plerocerci is presented, expanding data on intraspecific variation. The present report is the first record of from (new host record) and from Bulgaria (new geographical record). Recording only plerocerci with evaginated scoleces in the sticklebacks is consistent with the hypothesis that teleosts are paratenic hosts and not intermediate hosts of .