Light and electron microscopical description of Ceratomyxa labracis n. sp. and a redescription of C. diplodae (Myxosporea: Bivalvulida) from wild and cultured Mediterranean sea bass Dicentrarchus labrax (L.) (Teleostei: Serranidae)

Abstract

Two species of Ceratomyxa (Myxosporea: Bivalvulida) were found in the bile and gall-bladder of wild and cultured Mediterranean sea bass Dicentrarchus labrax. C. labracis n. sp. is described with fine, long lateral processes. The second species is determined as C. diplodae Lubat, Radujkovic, Marques & Bouix, 1989 and redescribed in absence of an adequate original description. Their taxonomic affinities with other species of the genus are discussed.

Ultrastructure and phylogeny of Ceratomyxa diplodae (Myxosporea: Ceratomyxidae), from gall bladder of European seabass Dicentrarchus labrax

“…The myxospores studied here presented similar measurements to those reported in the description from D. labrax, further coinciding with the observation of different shapes: myxospores are frequently crescentshaped, occasionally arcuate, with the rare occurrence of abnormal forms with 3 valves and 3 polar capsules. The only difference between this and the previous report is the number of polar filament coils, which are 3 to 4 according to the observations of Sitjà-Bobadilla & Álvarez-Pellitero (1993b). Here, the combined use of LM and TEM revealed the polar filament forming 8 to 9 coils organized in 2 rows.…”

“…The few exceptions usually produce lesions characterized by vacuolization, deformation, and necrosis of the gall bladder epithelial cells, as has been described for the infection of Ceratomyxa spp. in D. labrax, C. puntazzi in D. puntazzo, and C. dehoopi Reed et al, 2007 in Clinus superciliosus (Linnaeus, 1758) (Álvarez-Pellitero & Sitjà-Bobadilla 1993b, Reed et al 2007, Alama-Bermejo et al 2011). In the case of C. diplodae, Katharios et al (2007) reported high mortalities of D. puntazzo due to heavy infestations of the parasite in potentially immunosuppressed specimens, and Merella et al (2005) correlated C. diplodae with the enlargement of the gall bladder in fish intensively infected with the polyopisthocotylean Atrispinum salpae (Parona & Perugia, 1890).…”

“…In the above-mentioned geographic areas, 6 myxosporean parasites are known to infect D. labrax: Sphaero spora testicularis Sitjà-Bobadilla & Álvarez-Pellitero, 1990, which intensively infects the testes and causes castration (Álvarez-Pellitero & Sitjà-Bobadilla 1993a, Rigos et al 1999); S. dicentrarchi Sitjà-Bobadilla & Álvarez-Pellitero, 1992, which parasitizes the connective tissue, reducing the growth rate and increasing the possibility of secondary infections (Sitjà-Bobadilla & Álvarez-Pellitero 1992, Rigos et al 1999, Fioravanti et al 2004; Enteromyxum leei Diamant, Lom & Dyková, 1994, which causes enteritis associated with mass mortalities in several fish species, including D. labrax (Fioravanti et al 2006); Ortholinea labracis Rangel et al 2016, which was recently described from the urinary bladder and posterior kidney (Rangel et al 2016); and Ceratomyxa diplodae Lubat et al, 1989 andC. labracis Sitjà-Bobadilla &Álvarez-Pellitero, 1993, which infect the gall bladder (Álvarez-Pellitero & Sitjà-Bobadilla 1993b, Sitjà-Bobadilla & Álvarez-Pellitero 1993b. In the Indo-Pacific region, Kudoa iwatai Egusa & Shiomitsu, 1983 has also been reported infecting the muscle of D. labrax and is correlated with cases of food poisoning (Diamant et al 2005, Matsukane et al 2011, Suzuki et al 2012.…”

“…are considered relatively harmless, either because these parasites induce minimum tissue damage or, more likely, because no studies have investigated their pathogenicity. Consequently, little information is available on C. labracis and C. diplodae, besides their original descriptions (Lubat et al 1989, Sitjà-Bobadilla & Álvarez-Pellitero 1993b.…”

Molecular identification of cryptic species of Ceratomyxa Thélohan, 1892 (Myxosporea: Bivalvulida) including the description of eight novel species from apogonid fishes (Perciformes: Apogonidae) from Australian waters

“…Traditional bivalvulidan classification based on spore morphology alone to distinguish between closely related species is difficult due to the paucity of informative characters at the light microscopic level and the plasticity of spores Heiniger et al 2008;Sitja-Bobadilla and Alvarez-Pellitero 1993;Meglitsch 1960). Usually genetic variation is combined with morphological and/or biological differences to provide evidence for the recognition of novelty.…”