A new myxozoan, Ceratomyxa bohari sp. n., infecting the gall bladder of two-spot red snapper, Lutjanus bohar Forsskål, in the Red Sea off Saudi Arabia, is described using light microscopy and characterised genetically. The infection was recorded as mature spores floating free in the bile. The overall prevalence of infection of the type host was 19% (67 fish infected of 360 examined), with the highest prevalence in autumn (31%; 28/90) and the lowest in winter at 12% (11/90). Mature spores are slender and slightly crescent-shaped in the frontal view, with anterior and posterior margins tapered gradually to rounded valvular tips. Spore valves are unequal with a prominent sutural line. The spore dimensions are 3-4 μm (mean 3.5 μm) in length and 16-19 μm (mean 17 μm) in thickness. Two polar capsules are spherical, equal in size, 1.5 μm in diameter. Coils of the polar filament are indiscernible. The sporoplasm is binucleated and fills nearly one third of the extracapsular space restricted to the area below the capsules. The molecular analysis based on the small subunit rDNA (SSU rDNA) sequence revealed a close relationship with majority of species of Ceratomyxa Thélohan, 1892 and phylogenetic clustering with species from different geographical location. Thus, the shorter spore of the present Ceratomyxa species and the divergence of the SSU rDNA sequences were the distinctive features that separate it from all previously described species and identified this parasite as a new species of Ceratomyxa., Lamjed Mansour, Abdel-Azeem S. Abdel-Baki, Ahmad F. Tamihi, Saleh Al-Quraishy., and Obsahuje bibliografii
Myxobolus buckei sp. n. is described from the spinal column of Leuciscus cephalus (L.), Rutilus rutilus (L.) and Abramis brama (L.) from freshwater rivers in the North of England. The plasmodia develop within the remnants of the embryonic notochord in the intervertebral spaces. The spores are large, measuring (in µm) 14.0 ± 0.7 × 11.5 ± 0.6 (mean ± SD), smooth, round to ellipsoid in valvular view with several sutural edge markings. The polar capsules are pyriform and of equal size, measuring 7.5 ± 0.5 × 4.2 ± 0.2 (mean ± SD), with 11-12 turns of the polar filament arranged perpendicularly to the longitudinal axis of the polar capsule. The parasite has a large intercapsular appendix and large iodinophorous vacuole. The parasite can be differentiated from all known species of Myxobolus Bütschli, 1882 by a combination of the morphological characters defined. Infected fish show marked longitudinal compression of the body compared to uninfected individuals of the same year class, a feature which is pathognomonic for the disease. Histologically, host responses ranged from mild hypertrophy of the zygapophyseal process and expansion of the intervertebral membrane to complete hypertrophy and fusion of the vertebrae. Prominent notochord is present in the intervertebral spaces of infected fish and sporogony of the parasite leads to a vigorous focal inflammatory response involving proliferating fibroblast and osteogenic cells. The parasite causes a radial expansion of the centra and extensive dorsal and ventral outgrowths of the vertebrae leading to compression of the spinal cord and blood vessels running through the neural and haemal spines respectively. The parasite is considered highly pathogenic to juvenile cyprinids.