Morphometeric criteria and partial sequence of the 18S rRNA gene of Ceratomyxa sultani n. sp. from the gallbladder of Upeneus margarethae in the Arabian Gulf, with a note on its seasonal prevalence.

This paper describes a new coelozoic myxosporean parasite named Ceratomyxa sultani n. sp. isolated from the gallbladder of Upeneus margarethae sourced from the Arabian Gulf off Saudi Arabia. Of 104 U. margarethae specimens examined, 27 (26%) were infected, with the highest prevalence in winter and lowest in autumn. The pseudoplasmodia were disporous and irregularly elliptical in shape, with an average size of 22 × 17 µm. Mature spores were mostly elliptical with symmetrical valves and equal spherical polar capsules. Spores were 9 µm in length and 25 µm in thickness, while polar capsules were 4 µm wide with four filament coils. The paper further provides a morphological comparison with closely related Ceratomyxa spp. together with phylogenetic analysis based on the partial 18S rRNA sequence, which revealed that C. sultani n. sp. clustered within a robust clade of Ceratomyxa species from the Arabian Gulf and Red Sea or nearby geographic regions.

Ceratomyxa azevedoi n. sp. (Myxozoa: Myxosporea) parasitizing the gallbladder of Lutjanus ehrenbergii in the Arabian Gulf.

A novel myxosporean species, Ceratomyxa azevedoi sp. n. is described from the gallbladder of the blackspot snapper, Lutjanus ehrenbergii (Peters), captured from the Arabian Gulf off Saudi Arabia. A total of 45 (26.8%) out of 168 fish specimens were found to be infected with Ceratomyxa azevedoi sp. n., the highest prevalence being observed in winter (42.9%, 18/42) and the lowest in autumn (11.9%, 5/42). Mature spores appeared as crescent to slightly elliptical-shaped, measuring 5-7 (6) µm in length and 12 (10-14) µm in thickness, with spherical polar capsules containing three polar filament coils. The morphometric and morphological comparison with similar species revealed the taxonomic novelty of this form, suggesting that it should be considered as new species. The phylogenetic analysis of C. azevedoi sp. n., based on partial SSU rDNA sequences, revealed close genetic relatedness to C. buri with 91.3% homogeneity and to C. hamour, with 90.1% homogeneity.

Glugea jazanensis sp. nov. infecting Lutjanus bohar in the Red Sea: ultrastructure and phylogeny.

During a survey of the microsporean fauna of the two-spot red snapper Lutjanus bohar Forsskål, 1775, from the Red Sea off Jizan (Saudi Arabia), a species of Glugea Thélohan, 1891 was found that did not conform to any known species. The species is characterized by the presence of spherical xenomas (ca. 2-5 mm in diameter) in the host body cavity. Examination of the lifecycle stages and mature spores using light and transmission electron microscopy also revealed morphological characteristics typical of species of the genus Glugea. Spores were elongated-ovoid with a posterior vacuole surrounded by the polar filament coils. Mature spores were 4.5 (4.0-4.8) µm long and 2.5 (2.0-2.5) µm wide. The polar filament was isofilar with 28 to 30 coils, although in most cases 29 coils, organized in 3 rows. Phylogenetic study based on the partial sequence of the small subunit (SSU) rRNA gene clustered the new microsporidia within the clade grouping species of the genus Glugea. The comprehensive analysis of the parasite's ultrastructural characteristics, together with molecular data for the SSU rDNA gene, suggests that this parasite is a new species of the genus Glugea, for which the name Glugea jazanensis sp. nov. is proposed.

Morphological and molecular aspects of Ceratomyxa mehlhorni n. sp., a parasite of the golden trevally Gnathanodon speciosus in the Arabian Gulf off the Saudi Arabian coast, with data on its seasonal prevalence.

During a survey of the myxosporean fauna of the golden trevally Gnathanodon speciosus from the Arabian Gulf off Saudi Arabia, a species of Ceratomyxa that did not conform to any known species was recorded. The infection was detected as a large number of mature spores free-floating in the bile. Mature spores were hat- or helm-like in the frontal view with two short and unequal valves. The spores measured 8 (7-9) × 12 (10-14). The two polar capsules were spherical, equal in size and measured 3 (2-4) in diameter with three filament turns. Sporoplasm was binucleated and filled the whole extracapsular space. The small subunit ribosomal DNA sequence of this species did not match any available sequences in GenBank. The lowest genetic distance was 0.017, observed with Ceratomyxa moseri infecting Pomacentrus wardi from Australia's Great Barrier Reef. A maximum likelihood phylogenetic tree showed a close association between the new species and a variety of ceratomyxid species, including Ceratomyxa arabica reported from the Arabian Gulf. Given the morphological and molecular differences between this species and other Ceratomyxa spp., we proposed the present form was a new species and the name Ceratomyxa mehlhorni sp. n. for this parasite from the gallbladder of G. speciosus.

Morphology, seasonality and phylogenetic relationships of Ceratomyxa husseini n. sp. from the gall-bladder of Cephalopholis hemistiktos (Rüppell) (Perciformes: Serranidae) in the Arabian Gulf off Saudi Arabia.

During a survey of myxosporean parasites of marine fishes from the Arabian Gulf in Saudi Arabia, spores of Ceratomyxa husseini n. sp. were found in the gall-bladders of 50 out of 148 specimens (33.8%) of the yellowfin hind Cephalopholis hemistiktos (Rüppell) (Perciformes: Serranidae). The rates of infection showed a seasonal fluctuation, with the highest prevalence in winter and the lowest in autumn. The mature spores appeared arched in frontal view with rounded valve ends and a slightly discriminated curved suture line and measured 8-9 × 14-18 (9 × 16) µm. The two polar capsules were spherical and equal in size, 4-5 (4.5) µm in diameter. The polar filament showed four turns obliquely to the longitudinal axis of the capsules and the sporoplasm filled half of the entire spore cavity. Partial sequences of the small subunit rRNA gene of C. husseini n. sp. showed percentage of identity with other species of Ceratomyxa ranging between 79.8 and 92.7%. The morphometric and molecular data, in association, confirmed that the present new species differs from all other Ceratomyxa spp. reported to date.

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 %.

Molecular and morphometric characteristics of Ceratomyxa hamour n. sp. (Myxosporea: Bivalvulida) infecting the gallbladder of the orange-spotted grouper Epinephelus coioides from the Arabian Gulf, Saudi Arabia.

Ceratomyxa hamour n. sp. was found to infect the gallbladder of the orange-spotted grouper, Epinephelus coioides located off the Saudi Arabian coast of the Arabian Gulf. The infection was reported as a free-floating spore in the bile, and pseudoplasmodia were not observed. Mature spores were crescent-shaped and measured on average 7 µm in length and 16 µm in thickness. The polar capsule, meanwhile, had length to width measurements of 4 µm and 3 µm on average. A periodical survey was conducted throughout a sampling period between December 2012 and December 2013, with the results showing that the parasite was present throughout the year with a mean prevalence of 32.6%. The objective of this study was to characterize this new species based on its morphological and molecular differences from previously described species. Molecular analysis based on the partial sequence of the SSU rDNA gene, showed the highest similarity (97.8%) to Ceratomyxa buri, reported in the cultured yellow tail Seriola quinqueradiata in Japan. Indeed, C. buri and the new species described here formed an individual cluster with a high degree of bootstrap support. This is the first reported species of genus Ceratomyxa from the Arabian Gulf fishes off Saudi Arabia.