Prosorchis palinurichthi Kurochkin, Parukhin & Korotaeva, 1971 (Digenea, Sclerodistomidae): Ultrastructure of the mature spermatozoon

This study presents the ultrastructure of the mature spermatozoon of Prosorchis palinurichthi (Digenea: Hemiuroidea: Sclerodistomidae), parasite of the digestive tract of the teleost fish Schedophilus velaini ( Sauvage, 1879) (Centrolophidae) captured in the Atlantic Ocean, near Dakar (Senegal). This is a first report of P. palinurichthi from Senegal and from this host species. The mature spermatozoon of P. palinurichthi is filiform, tapered at both ends and exhibits the general pattern described in the hemiuroids: two axonemes of the 9 + ‘1’ pattern of trepaxonematans, a nucleus, a mitochondrion, external ornamentation of the plasma membrane in the anterior region of the spermatozoon and parallel cortical microtubules disposed in one side of the spermatozoon except in the anterior spermatozoon extremity and in the mitochondrial region. However, the particularities of the spermatozoon of P. palinurichthi are the presence of cortical microtubules at the anterior extremity, a great number of cortical microtubules (up to 25) in the region II of the spermatozoon, an elongate nucleus longer than the mitochondrion and the absence of spinelike bodies. Our results are discussed in context with those of previous studies in the Digenea in general and particularly in the Hemiuroidea.