Description of a new species of Dolichorchis (Digenea, Diplostomidae) in the cocoi heron, Ardea cocoi

Dolichorchis lacombeensis sp. nov., a digenean parasite of the gut of the cocoi heron, Ardea cocoi (L.), is described as a new species from Buenos Aires Province, Argentina. This new species most closely resembles D. buteii and D. tregenna in the dis-tribution of the vitelline follicles, which reach the intestinal bifurcation in the forebody. D. buteii can be distinguished from D. lacombeensis sp. nov. by the distribution of the vitelline follicles in the hindbody, which are concentrated in midline, by the presence of a sphincter in genital pore and by the size of holdfast organ and posterior testis, which are larger, (240–400 × 176–240 and 315–464 × 240–410 µm, respectively). D. tregenna differ from the new species by their larger measurements (pseudosuckers ’ length 90–100, pharynx 52–90 × 50–70 and eggs 89–104 × 48–68 µm)