Redescription of Ptychobothrium belones (Dujardin, 1845) (Cestoda: Bothriocephalidea) from needlefishes (Beloniformes: Belonidae) in the Mediterranean Sea.

The bothriocephalidean tapeworm Ptychobothrium belones (Dujardin, 1845) Lönnberg, 1889 is redescribed on the basis of new materials collected from the intestine of the Mediterranean needlefish Tylosurus imperialis (Rafinesque) (Beloniformes: Belonidae) off Tunisia in the central Mediterranean Sea. This species is characterised by a laterally compressed hexagonal to fan-shaped scolex with an apical disc and two well-developed bothria, an oval ovary and numerous testes arranged in lateral and median fields. The typical diagnostic feature of P. belones is the medullary yolk follicles located between the muscle fibres of the internal longitudinal muscles (paramuscular) and the uterine duct strongly sinuous, S-shaped in mature proglottides. New molecular data (partial sequence of nuclear large subunit ribosomal RNA gene) confirmed the close relationship with specimens previously collected by Brabec et al. (2006, 2015) from the banded needlefish Strongylura leiura (Bleeker) off the Maldives, Indian Ocean, but these specimens are most likely another species. Thus, Ptychobothrium belones as previously reported represents most likely more than one species and its cosmopolitan distribution and host specificity revised by Kuchta et al. (2008b) should be revisited. The type material of P. belones was reported as collected in Mediterranean Sea off Sète, France, from Belone belone (Linnaeus); however, this host was probably misidentified, being confused with morphologically similar small specimens of T. imperialis. This study confirms that P. belones is an exclusive parasite of needlefishes (Belonidae) but at least one further species infecting S. leiura may exist.

Axinoides euzeti n. sp. (Monogenea: Axinidae) from the gills of the needlefish Tylosurus acus imperialis (Rafinesque) (Belonidae) off Tunisia, with an updated list of hosts and localities for Axinoides spp.

A new axinid monogenean species, Axinoides euzeti n. sp. from the gills of the Mediterranean needlefish Tylosurus acus imperialis (Rafinesque) off the Tunisian coast is described. The new species is most similar in general morphology to A. meservei Price, 1946 from Tylosurus crocodilus fodiator Jordan & Gilbert off the Atlantic Ocean and to A. kola Unnithan, 1957 from Ablennes hians (Valenciennes) off the Indian Ocean. It can be differentiated from A. meservei by the shape of anterior male genital complex armed with several rows of curved spines on the cirrus rather than 3 to 4 rows of slender spines, in having a fewer testes (87-94 vs more than 100 in the drawing of A. meservei) and a body size twice longer than wide. It differs also from A. kola which have a single row of small spines in the cirrus, in having fewer and wider clamps and fewer and smaller testes. A. euzeti represents the first record of a representative of this genus in the Mediterranean Sea. In addition, taxonomic keys and an updated list of hosts and geographic localities for Axinoides species is presented.

First detailed data on metazoan parasites of the rare species short beaked garfish Belone svetovidovi (Teleostei: Belonidae) from Tunisian coast, Central Mediterranean Sea.

Forty five specimens of the short beaked garfish Belone svetovidovi, a rare belonid species largely confused with the garfish Belone belone from Tunisian coast Sea were examined for metazoan parasite. Nine metazoan parasites species were identified: one monogenean (Axine sp.), 4 digeneans (Lecithostaphylus retroflexus, Tergestia acanthocephala, Aponurus laguncula and Condylocotyla pilodora metacercaria), one copepod (Bomolochus bellones), one isopod (Irona nana), one acanthocephalan (Telosentis exiguus) and one nematod Hysterotylacium sp. Most of parasite species were new records for B. svetovidovi in Tunisia. In the parasite fauna of B. svetovidovi, digenean C. pilodora metacercaria was the most prevalent species (42%) followed by Monogenea Axine sp. (36%). The total length of the host did not influence parasitic infection in B. svetovidovi. The metazoan parasite composition of B. svetovidovi revealed great similarity than those of B. belone from Tunisia supporting same ecological behavior of both hosts.

Sclerodistomoides pacificus Kamegai, 1971 (Sclerodistomoididae Gibson & Bray, 1979) and Tetrochetus coryphaenae Yamaguti, 1934 (Accacoeliidae Odhner, 1911), two rarely reported digeneans from Tylosurus acus imperialis (Rafinesque) (Belonidae), and a list of helminth parasites of Tylosurus acus (Lacépède).

Two rarely reported digenean parasites are redescribed: Sclerodistomoides pacificus Kamegai, 1971 (Sclerodistomoididae Gibson & Bray, 1979) from the gall bladder and Tetrochetus coryphaenae Yamaguti, 1934 (Accacoeliidae Odhner, 1911) from the digestive tract of the Mediterranean needlefish Tylosurus acus imperialis (Rafinesque) off Tunisia. Sclerodistomoides pacificus and T. coryphaenae represent new host and geographical records for T. a. imperialis off the Tunisian coast. A complete list of the helminth parasites found in T. a. imperialis and those reported from other subspecies of Tylosurus acus (Lacépède) throughout their wide distributional range is presented. It includes data for T. a. acus (Lacépède), T. a. imperialis, T. a. melanotus (Bleeker) and T. a. rafale Collette & Parin and comprises 46 parasite taxa. Among these, 15 species were recorded from T. a. imperialis off Tunisia.

Nudaciraxine imperium sp. n. (Monogenea: Axinidae) from the gills of Mediterranean needlefish Tylosurus acus imperialis (Teleostei: Belonidae).

Nudaciraxine imperium sp. n. (Monogenea: Axinidae) is described from the gills of the needlefish Tylosurus acus imperialis (Rafinesque) caught in the Gulf of Gabès, Tunisia. This new species mainly differs from both previously described species, Nudaciraxine gracilis (Linton, 1940) Price, 1962 from Strongylura marina (Walbaum) and Nudaciraxine cabosanlucensis Payne, 1990 from Ablennes sp., by having more testes (42 vs. 20-22 and 32, respectively). Nudaciraxine imperium also differs from N. gracilis by having a median vaginal pore (submedian in N. gracilis), narrower clamps (52-70 microm vs. 75-100 microm) and differently shaped haptoral lateral hamuli. From N. cabosanlucensis it can be distinguished by a J-shaped rather than U-shaped ovary, a longer cirrus pouch (125-190 microm vs. 64-70 microm), an oesophageal bifurcation slightly anterior to genital complex (immediately after pharynx in N. cabosanlucensis) and a wider guard on the lateral hamuli. In agreement with Payne (1990), the diagnosis of the genus Nudaciraxine Price, 1962 is amended as follows: vaginal pore dorsal, median to submedian, armed or not with horn-like spines. This is the first report of the genus Nudaciraxine in the Mediterranean Sea. The potential use of axinid monogeneans as biological tags for subspecies of belonid fishes is discussed.