Morphological Redescription and Phylogenetical Position of Ceratomyxa truncata Thelohan (1895) and Coccomyxa morovi Léger and Hesse, 1907 (Myxozoa: Myxosporea) Infecting the Gall Bladder of Sardina pilchardus (Walbaum) from Tunisian Coast.

PURPOSE: Two myxosporean species have been, so far, independently reported from the gallbladder of the European pilchard, Sardina pilchardus (Walbaum) (synonym Clupea pilchardus) in the Northern shore of the Mediterranean Sea; Ceratomyxa truncata Thélohan, and Coccomyxa morovi Léger and Hesse, 1907. The two species were described with incomplete morphological data and based only on line drawings of their mature myxospores. METHODS: During a parasitological survey in the Southern shores of the Mediterranean coast in the gulf of Gabès off Tunisia, two coelozoic myxosporean species were found in the European pilchard and described using morphological and molecular phylogenetic tools. Morphological characterization was based on the mature myxospore study and some vegetative stages. The SSU rDNA sequences were performed for molecular and phylogenetic study. RESULTS: The most frequently encountered species belongs to the genus Ceratomyxa Thelohan, 1892. The second species belongs to the genus Coccomyxa. Morphological examinations, allowed us to match these two recorded species with Ceratomyxa truncata and Coccomyxa morovi, respectively, as previously described in the same host species referring to the original manuscripts instead of some morphological differences. Molecular analyses based on the partial SSU rDNA sequences did not much with any of the previously reported myxozoan sequences. Phylogenetic analysis positioned C. truncate in a well-supported clade including Ceratomyxa ssp. from Mediterranean Sea, while C. morovi was positioned on the basis of the subclade grouping all Coccomyxidae species. CONCLUSION: We provided herein a first morphological redescription of Ceratomyxa truncata and Coccomyxa morovi parasite of Sardina pilchardus from the Southern shores of the Mediterranean Sea and we successfully obtained the SSU rDNA sequences of these two species and positioned them in the phylogenetic tree.

Molecular and morphological characterisation of two species of the genus Ellipsomyxa Køie, 2003 (Ceratomyxidae) from the gall-bladder of Liza saliens (Risso) off Tunisian coasts of the Mediterranean.

During examination of some species of the family Mugilidae, two coelozoic myxozoans were observed in the gall-bladder of the leaping mullet, Liza saliens (Risso). Spore morphology allowed us to allocate them to the genus Ellipsomyxa Køie, 2003, one of which is described here as new. Ellipsomyxa kalthoumi n. sp. was observed forming globular pseudoplasmodia and free spores floating in the bile. Mature spores are ellipsoidal, measuring 13-21 × 10-15 (17.2 × 13.2) µm and possessing two equal spherical polar capsules, 5-6 (5.5) µm in diameter, opening subterminally in opposite directions, with nine polar filament coils. Morphological data and molecular analysis of the small subunit rDNA sequences helped identify this parasite as a new species of Elliposmyxa. The second species identified as E. mugilis (Sitjà-Bobadilla & Alvarez-Pellitero, 1993) has oval spores with rounded ends, measuring 10-11 × 7-9 (10.5 × 8.0) µm and possessing two polar subspherical capsules, 2.7-3.0 (2.8) µm in diameter, opening subterminally in opposite directions. Spore morphometry and molecular study of the small subunit (SSU) of the rRNA gene identified this species as E. mugilis described from the same host in the Western Mediterranean off Spain. Phylogenetic analysis revealed Elliposmyxa as a monophyletic clade and showed that E. mugilis, E. syngnathi Køie & Karlsbakk, 2009, E. adlardi Whipps & Font, 2012 and E. gobii Køie, 2003 group in a subclade containing the Tunisian isolate of E. mugilis whereas E. kalthoumi n. sp. appears in a second subclade together with four Australian species, E. maniliensis Heiniger & Adlard, 2014, E. apogoni Heiniger & Adlard, 2014, E. nigropunctatis Heiniger & Adlard, 2014 and E. arothroni Heiniger & Adlard, 2014.

Ceratomyxa tunisiensis n. sp. (Myxosporea: Bivalvulida) from the Gallbladders of Two Carangid Fish Caught Off the Coast of Tunisia.

A new coelozoic Myxozoan species, Ceratomyxa tunisiensis n. sp., was found infecting the gallbladders of two carangid fish, Caranx rhonchus and Trachurus trachurus (Perciforme, Carangidae), from the Gulf of Gabès, on the southern coast of Tunisia. The parasite develops in spherical mono-, diplo-, or polysporic tropozoites in the gallbladder of the hosts. Mature spores are typical of the genus Ceratomyxa. They are transversely elongated and narrowly crescent-shaped with a slightly convex anterior and concave posterior, and measure 23 ± 0. 27 (20-25) µm width × 6 ± 0.26 (5-8) µm in length. Spore shell valves are symmetrical with rounded ends. Two spherical polar capsules situated on either side of the sutural line measure 2.2 µm (2.0-3.0) in diam. Periodical sampling of C. rhonchus and T. trachurus from Marsh 2012 to February 2013 showed that infection due to C. tunisiensis occurs in 59% and 69% of the examined fish, respectively. Molecular analysis based on the small subunit (SSU) rRNA sequence shows high genetic divergence with all other ceratomyxid species. A Maximum Likelihood phylogenetic tree shows association with the species C. leatharjecketi Fiala, kova, Kodadkova, Freeman, Bartosova-Sojkova, and Atkinson, 2015 reported from the gallbladder of Aluterusmonoceros (L.) caught in the Andaman Sea, off Malaysia. Nonetheless, the SSU rRNA sequences of C. tunisiensis and C. leatharjecketi have only a 90% similarity.

Kudoa azevedoi n. sp. (Myxozoa, Multivalvulida) from the oocytes of the Atlantic horse mackerel Trachurus trachurus (Perciformes, Carangidae) in Tunisian coasts.

A new species Kudoa azevedoi sp. n. (Myxozoa, Multivalvulida) is described in Trachurus trachurus Linnaeus, 1758 (Carangidae) from fishing harbors in Tunisian coasts using spore morphology and SSU rDNA sequence data. The parasite occurs only in ovaries within oocytes of mature and immature specimens. Spores are quadrate in shape in apical view with rounded edges, having four shell valves and four symmetrical polar capsules. They are of small sizes and measure 3.5±0.41 (3-4.2)×4.5±0.44 (4-5.2) length by width. The polar capsules are pyriform in shape measuring 1.5±0.22 (1.5-2)×0.75±0.14 (0.5-1) µm. Infected oocytes are hypertrophied, whitish colored, and filled with mature spores. Plasmodia are tubular and ramified from the inner membrane toward the center of the oocyte. Phylogenetic analysis based on small subunit ribosomal DNA sequences shows the highest similarity (96%) with the ovary parasite Kudoa ovivora. Some morphological details and spore dimensions support the creation of a new species in the genus Kudoa. Mean prevalence among examined females is of about 55.5%. It varies between localities and length of fish. The present myxosporea is the second Kudoa species reported in fish ovaries.