Two new Myxobolus spp. (Myxozoa: Myxobolidae) from white bream, Blicca bjoerkna (Linnaeus, 1758) developing in basifilamental location of gills

Abstract

Two new Myxobolus species, M. bjoerknae sp. n. and M. lamellobasis sp. n. have been described from the gills of white bream, Blicca bjoerkna . Plasmodia of M. bjoerknae sp. n. developed in the connective tissue inside the cartilaginous gill arch, while plasmodia of M. lamellobasis sp. n. seem to start their development in the multilayered epithelium between two lamellae close to the base of gill filaments. Then they may bulge out of the interlamellar space fused to a large bulk locating at the base of filaments. The large, ellipsoidal spores of M. bjoerknae sp. n. 17.4 × 13.1 µm in size, resembled the spores of other species developing in the gill arch (e.g. M. fundamentalis , M. gayerae , and M. pfeifferi ), but differed from them in its 18S rDNA sequence. Roundish spores of M. lamellobasis sp. n. with a size of 11.1 × 8.6 µm resembled the spores of M. impressus developing interlamellarly and the spores of M. rotundus, M. parviformis , and M. muellericus having intralamellar localization. However, the detected genetic difference clearly distinguished it from the other species developing in similar tissue location. The phylogenetic location of the two newly described species seems to correlate both with spore shape and fish host species.