Ultrastructural study of the spermatozoon of the digenean Enodiotrema reductum Looss, 1901 (Platyhelminthes, Plagiorchioidea, Plagiorchiidae), parasite of the green turtle Chelonia mydas (Linnaeus, 1758) in Senegal.

This study describes the ultrastructural organisation of the spermatozoon of a digenean Enodiotrema reductum (Pligiorchiida: Plagiorchiidae) from the green turtle Chelonia mydas (Linnaeus, 1758). This is the first report of E. reductum from Senegal. The mature spermatozoon of E. reductum is filiform and exhibits two axonemes of the 9 + "1" pattern of the Trepaxonemata, a nucleus, parallel cortical microtubules, an extramembranar ornamentation associated with spine-like bodies and granules of glycogen, among other ultrastructural features. The spermatozoon of E. reductum is distinguished by the presence of a moniliform mitochondrion composed of a bulge associated with a long cord and of a central cytoplasmic expansion. This work represents the first utrastructural study of any representative of the large family Plagiorchiidae. Our results are compared with previously published data on spermatozoa of other digenean taxa.