Authors

Discussion

Cardiocephaloides Sudarikov, 1959 is a small genus of digeneans within the Strigeidae Railliet, 1919 (Digenea), containing seven species that have been described from birds hosts: Cardiocephaloides brandesii (Szidat, 1928), C. hilli (Johnston, 1904), C. longicollis (Rudolphi, 1819), C. medioconiger (Dubois & Perez-Vigueras, 1949), C. megaloconus (Cable, Connor & Balling, 1960), C. ovicorpus Dubois & Angel, 1972 and C. physalis (Lutz, 1927). In South Africa, metacercariae of the latter have been found in the eyes of pilchards (Sardinops sagax (Jenyns, 1842)), and adults have been reported to cause mortalities of African penguin chicks [Spheniscus demersus (L.)]. During the present study, metacercariae of this genus were found in the eye vitreous humour and brain of the intertidal fish Clinus superciliosus (L.) and in the eye vitreous humour of Clinus cottoides (Valenciennes, 1836), collected along the South African coast. Morphological and molecular analyses (28S rDNA, ITS1-5.8S-ITS2, cox1 mtDNA) revealed they belong to two species: C. physalis and an unidentified species of Cardiocephaloides. We therefore provide the first detailed morphological description associated with DNA sequences of Cardiocephaloides spp. from South Africa and the first report of clinid fishes being intermediate hosts for digeneans of the genus Cardiocephaloides. We also confirmed that the diversity of Cardiocephaloides in South Africa is higher than previously recorded. Based on molecular sequence data for a more variable gene (cox1), the broad geographic distribution of C. physalis was confirmed, as this species has been reported in both Africa and South America. Also, Cardiocephaloides sp. was found to be conspecific to an unidentified species found from whelks in New Zealand, based on ITS1 sequence analyses. Overall, the results of our study strongly suggest that intertidal fishes, such as Clinus spp., play an important role in the life cycles of digeneans, thus further exploration of their digenean diversity will provide valuable data for future taxonomic and ecological research. The work presented here was recently published in Folia Parasitologica 2021, 68: 007.