Importance of the paratenic host in the biology of Bothriocephalus gregarius (Cestoda, Pseudophyllidea) a parasite of the turbot

Bothriocephalus metacestodes were found in the intestine of two species of goby along the French coasts: Pomatoschistus marmoratus and P. minutas. A biochemical study showed that the metacestodes belong to the species B. gregarius, whose adult form infects the turbot ( Psetta maxima). Epidemiological and other data suggest that young turbot become infected by eating copepods containing proplerocercoids; older turbot become infected by eating infected gobies. In gobies the parasite develops from a proplerocercoid to a strobilating plerocercoid. Gobies are thus paratenic hosts though the parasite develops within them. Maturation of worms in what were once paratenic hosts could be a mechanism for sympatric speciation in the B. scorpii complex.