Host-parasite relationship of Ceratomyxa puntazzi n. sp. (Myxozoa: Myxosporea) and sharpsnout seabream Diplodus puntazzo (Walbaum, 1792) from the Mediterranean with first data on ceratomyxid host specificity in sparids.

Sparidae are economically important fishes to both, fisheries and aquaculture in the Mediterranean. Species diversification is an important strategy for the development of Mediterranean aquaculture. One of the species recently introduced is the sharpsnout seabream Diplodus puntazzo (Walbaum, 1792). During a parasitological study of fish from the Gulf of Valencia and the Mar Menor (Spain), myxozoan spores belonging to the genus Ceratomyxa were found in the gall bladder of D. puntazzo. A morphological description of the spores, which includes histology and transmission electron microscopy (TEM) as well as molecular (SSU ribosomal DNA) data resulted in the erection of a new species, Ceratomyxa puntazzi n. sp. A histopathological study of C. puntazzi n. sp. infection in D. puntazzo showed that the parasite causes necrosis and loss of epithelial cells in the gall bladder, and provokes a pericholangitis in the liver tissue surrounding the bile ducts. Furthermore, molecular data obtained from C. puntazzi n. sp. and three other ceratomyxids from the closely related fish species Diplodus annularis L. and Sparus aurata L. which share the same habitat suggest that the genus Ceratomyxa is host-specific in sparids, which agrees with data previously obtained from Serranidae, Labridae and Pomacentridae, and that ceratomyxid species from sparids in the Mediterranean originated from a common ancestor.