First report of Kudoa species (Myxozoa, Multivalvulida) infection in purple-spotted Bigeye (Priacanthus tayenus) from the Saudi Arabian Gulf.

The purple-spotted bigeye, Priacanthus tayenus, is a marine benthic fish native to the Indian and Pacific Oceans, including the Arabian Gulf in Saudi Arabia. This study identified a myxozoan parasite infecting wild P. tayenus from the Saudi Arabian Gulf. These parasites produced spherical to ovoid-shaped, white plasmodia enclosed within pseudocysts in the fish musculature. The annual infection rate was 5.1%, with the highest prevalence in summer (7.6%), followed by spring (6%), and autumn (2.5%), while no infections were observed in winter. The number of plasmodia per fish ranged from 100 to 150 (135.1 ± 16.2). Their dimensions were 4-4.7 mm (4.3 ± 0.3 mm) in length and 4.5-7 mm (6 ± 1.1 mm) in width. Milky-colored exudates within the plasmodia contained mature spores measuring 8-9 µm (8.6 ± 0.4 µm) x 6-7.5 µm (6.9 ± 0.5 µm). The polar capsules of the spores exhibited dimensions of 2-5 µm (3.5 ± 0.5 µm) x 2.5-4.5 µm (3 ± 0.45 µm). Both morphological and genetic analyses confirmed these plasmodia as a novel Kudoa species. Histopathological examination revealed atrophy in the surrounding muscles without an inflammatory response. This study documents the first occurrence of a novel Kudoa sp. in P. tayenus at the Jubail landing site in Saudi Arabia, emphasizing the need for further surveillance and investigations to elucidate its pathogenesis and implications for wild fish stocks.

Huffmanela selachii n. sp. (Nematoda: Trichosomoididae: Huffmanelinae): A new species infecting the skin of the great hammerhead shark (Sphyrna mokarran) and the blacktip reef shark (Carcharhinus melanopterus) in the Arabian Gulf, off-shore Saudi Arabia.

From January 2017 - December 2019, 75 out of 850 (8.8 %) great hammerhead sharks from the Arabian Gulf had skin lesions of black irregular discolorations on the ventral surface of the head. The lesions consisted of pencil-like lineations often advancing forward by about 2 mm in back-and-forth looped scribbles often forming a relatively linear bands of about 5-7 cm wide. Similar lesions were also found in the blacktip reef shark from the same area within the same period, and consisted of straight to irregular black lines, extended indiscriminately across the skin of the sharks. Microscopic examination of the skin revealed the presence of dark-brown eggs exhibiting the spindle or ellipsoidal eggs characteristic of Huffmanela sp. The morphometrics of eggs from both hosts were similar (62.9-89.9 µm long and 29.3-56.1 µm wide). The eggshells were smooth with polar plugs protruding or not, with an abruptly truncated crown-like or shoulder-like collar surrounding the plug. The eggs were only found in the epidermal layer of the skin. Based on the unique morphometrics of the eggs, we report a new species, named: Huffmanela selachii n. sp.. This appears to be the first report of Huffmanela from either the great hammerhead shark or the blacktip reef shark, and the third reported Huffmanela in sharks from the Arabian Gulf. It is also one of few species reported from connecting waters of the greater Indian Ocean. This new finding contributes to our understanding of the diversity and ubiquity of Huffmanela sp. in marine creatures.

Morphological and pathological appraisal of Huffmanela sp. (Nematoda: Trichosomoididae) infecting orange-spotted grouper (Epinephelus coioides, Hamilton, 1822) at Jubail Province, Saudi Arabia: a case report.

This paper is conducted for identifying the parasite which collected during regular routine inspection for the hygienic condition and health status of fish in 2019 at the central fish market shops at Jubail city, Saudi Arabia. Samples from an orange spotted grouper (Epinephelus coioides) fish showed heavy black streaks between the muscle fibers that was considered unmarketable and rejected by the consumer after had been cut and prepared for sealing. The black discolorations were in the form of heavy diffused focal black spots or forming threads of variable sizes embedded in the entire whole-body musculature of the fish. These samples were subjected to parasitological and pathological evaluation. The parasitological examination of the affected muscular tissues revealed infection by Huffmanela spp. eggs. The parasitic infection was identified on the bases of the morphological and ultra-structural characters of the eggs. The examination of the affected fish showed multifocal black parasitic remnants between the muscle fibers. The parasitic fragments were distributed all over the fish flesh either superficially in subcutaneous area or deep inside the muscular tissue and they have been concentrated in the flesh around the vertebral column. In conclusion; this case report confirmed the occurrence of Huffmanela spp. infection in the muscles of Epinephelus coioides by using light and scanning electron microscopy. Further molecular assessment is recommended.