The occurrence of two opecoeliid digeneans in Mullus barbatus and M-surmuletus from the Spanish south-eastern Mediterranean

The infection by Opecoeloides furcatus and Poracanthium furcatum (Opecoelii dae) was studied in 121 Mullus barbatus and 113 M. surmuletus collected fro m the Spanish south-eastern Mediterranean. The prevalence of infection was most frequent in M. surmuletus with values of 81.42% for O. furcatus and 38 .05% for P. furcatum. In M. barbatus the prevalences of O. furcatus and P. furcatum were 54.54% and 14.88% respectively. Statistically significant dif ferences were found between the infection of the two hosts with P. furcatum . No significant differences in worm burdens could be attributable to host size or to seasonal changes, although a lower infection of M. barbatus by O . furcatus occurred in the autumn. Furthermore, the electrophoretic mobilit y of the enzyme malic dehydrogenase (MDH) was also studied and both digenea ns presented different patterns, corresponding in both cases to homozygotic genotypes.