Development of Anguillicola crassus (Dracunculoidea, Anguillicolidae) in experimentally infected Balearic congers Ariosoma balearicum (Anguilloidea, Congridae)

The development of Anguillicola crassus in experimentally infected Ariosoma balearicum (Anguilloidea, Congridae) kept in seawater was studied in the l aboratory. In parallel trials the effect of water salinity on the developme nt of larval A. crassus in European eels Anguilla anguilla was also investi gated using eels kept in seawater of a salinity of 34 parts per thousand. B oth eel species were orally inoculated with L-3 larvae of A. crassus and th en maintained for up to 3 mo at 18 degrees C in seawater. 110 d post infect ion, no adult but larval (L-3 and L-4) stages of A. crassus were detected i n the swimbladder wall of Balearic congers, although this period of time wa s sufficient for the parasites to develop to the adult stage in European ee l kept in seawater. The results presented suggest that the definitive host specificity of A. crassus comprises species of the family Anguillidae (i.e, the genus Anguilla), but not members of the Congridae. Theoretically howev er, A. balearicum might serve as a metaparatenic host. Factors determining the definitive host range of A. crassus remain to be elucidated, Water sali nity does not seem to act as a factor affecting definitive host specificity once the parasite has become ingested by the eel.