Morphology, phylogeny and seasonal prevalence of Ceratomyxa arabica n. sp. (Myxozoa: Myxosporea) infecting the gallbladder of Acanthopagrus bifasciatus (Pisces: Sparidae) from the Arabian Gulf, Saudi Arabia.

A new myxozoan species was recovered from the gallbladder of Acanthopagrus bifasciatus from the Arabian Gulf in Saudi Arabia. The overall prevalence of infection was 28.6 % (32/112), with the highest prevalence 42.9 % (12/28) in winter and 10.7 % (3/28) as the lowest in autumn. The new species is described using its morphological characteristics and small subunit (SSU) rDNA. Spores of Ceratomyxa arabica n. sp. are stubby-shaped with unequal shell valves, 8 (7-9) μm in length × 12 (10-14) μm in thickness. Polar capsules are sub-spherical, unequal, 3 (2.5-3.5) × 2 (1.5-2.5) μm. The polar filament has three turns and is slightly slanted towards the longitudinal axis of the capsules. The small subunit rDNA (SSU rDNA) sequence confirms that the present species is a member of the genus Ceratomyxa, being most closely related to Ceratomyxa cardinalis with a sequence similarity of 97.77 %.