Myxobolus allami sp. n. is described from the intestinal wall of the silvery black porgy, Sparidentex hasta (Valenciennes), off Saudi Arabian coast of Arabian Gulf. Two of 20 examined fish were found to be infected with irregular-shaped plasmodia 3-8 mm long × 2-3 mm wide. Mature myxospores are subspherical to elliptical in the valvular view and oval in the sutural view, and are 11-13 (12) µm long, 7-8 (7.5) µm wide and 10-12 (10.8) µm thick. Spores have relatively thin valves and mostly (~ 72%) end with short caudal appendages of ~3 µm long. The spores also have two polar capsules, which are oval to elliptical and measure 5-7 (5.7) µm in length and 2-3 (2.7) µm in width. Polar filaments are coiled, with three turns. Transmission electron microscopy revealed that caudal appendages originated from the sutural edge at the posterior pole of the myxospore with density similar to that of its valves. The SSU rRNAgene sequence of the present species does not match any available sequences in GenBank. Phylogenetically, this species is sister to Myxobolus khaliji Zhang, Al-Qurausihy et Abdel-Baki, 2014 within a well-supported clade of Myxobolus-Henneguya with species infecting marine fishes. The combination of molecular data and morphological differences between this and other species of Myxobolus Bütschli, 1882 lead us to propose that the present form be established as a new species, M. allami. The present study also provides more evidence for the idea that caudal appendages cannot be reliably used to distinguish the species of the genera Myxobolus and Henneguya Thélohan, 1892.
Four out of twenty (20%) specimens of the lizard Scincus hemprichii Wiegmann, collected in Saudi Arabia were infected with a previously undescribed species of Choleoeimeria. Oocysts of Choleoeimeria jazanensis sp. n. are cylindroidal, 26 × 15 µm, with a smooth bilayered wall and a shape index of 1.7. Oocyst residuum and micropyle are absent. Sporocysts are subspherical, 10 × 7 µm, with a shape index of 1.3. The Stieda body is absent. Sporozoites are banana-shaped, 10 × 3 µm, with one refractile body and enclosed the fine granulated sporocyst residuum. The endogenous development is confined to the gall bladder epithelium, with infected cells being displaced from the epithelium layer towards lumen. Mature meronts are subspherical and estimates to produce 9-12 merozoites. Microgamonts are spherical in shape with diameter of 13 µm. Macrogamonts are subspherical with a prominent nucleus in centre and wall-forming bodies at periphery.
Oocyst morphology and endogenous developmental stages are described for Choleoeimeria salaselensis sp. n. from the gall bladder of 10 horned vipers, Cerastes gasperettii Leviton and Anderson, in Saudi Arabia. Sporulated oocysts are ellipsoidal, 23 × 15 (22-25 × 14-17) µm, length/width ratio (L/W) 1.5 (1.4-1.6), each with 4 sporocysts (Eimeria-like), but lack a micropyle, polar granules and oocysts residuum. Sporocysts are ellipsoidal, 8 × 5 (7-9 × 5-6) µm, L/W 1.5 (1.4-1.6), and Stieda, substieda and parasubstieda bodies are all absent, but a longitudinal suture, which divided the sporocysts into 2 plates, is present. Endogenous development is confined to epithelial cells in the bile duct and gall bladder; mature meronts were 11 × 7 µm, each with 10-16 merozoites, microgamonts were ~12 µm wide, and macrogamonts were ~16 µm wide with a prominent nucleus and wall-forming bodies. Given these two diagnostic features, sporocysts with a suture and composed of two plates and endogenous development limited to the biliary epithelium, we believe this coccidium is best classified as a member of Choleoeimeria Paperna et Landsberg, 1989. There are 5 known Eimeria species from vipers that have sporocysts somewhat similar in size to those of our new form, but all of them have much larger oocysts and larger sporocysts, some of which differ significantly in shape; there are not yet any Choleoeimeria species known from the Viperidae.
To date, three species of Isospora Schneider, 1881 have been described from lizards of the genus Acanthodactylus Wiegmann. Two of these, although representing separate species parasitizing two different hosts, Acanthodactylus boskianus Daudin in Egypt and A. schmidti Haas in Saudi Arabia, were described under the name Isospora acanthodactyli. The third species is Isospora abdallahi Modrý, Koudela et Šlapeta, 1998 from A. boskianus in Egypt. In the present study, Isospora alyousifi nom. n. is proposed to accommodate Isospora acanthodactyli Alyousif et Al-Shawa, 1997 (homonym of I. acanthodactyli Sakran, Fayed, El-Toukhy et Abdel-Gawad, 1994) and its redescription based on newly collected material is provided.
This paper describes the fine structure of oocysts of Nematopsis sp. (Apicomplexa, Porosporidae) found in the abductor muscles of seawater clams, Meretrix meretrix (Linnaeus, 1758) (Veneridae), collected near the city of Dammam (6°17'0''N, 50°12'0''E) in the Arabian Gulf off the coast of Saudi Arabia. Oocysts of an ellipsoidal shape were found among myofibrils of the abductor muscles of infected clams. Each oocyst is composed of an oocyst wall surrounding a single uninucleate vermiform sporozoite located in the lumen of the oocyst wall. The thin oocyst wall (0.70-0.85 µm thick) is composed of homogenous electron-lucent material formed by three layers of equal-thickness. The oocyst wall contains a plano-convex opercular-like structure about 2.5 µm in diameter and 0.75-0.90 µm thick, composed of a homogenous material with moderate electron density. The oocyst is of an ellipsoidal shape and is 15.6 ± 0.6 µm long and 11.1 ± 0.7 µm wide. Externally, the oocyst wall is surrounded by a complex dense network of numerous anastomosed microfibrils, which are attached to the oocyst wall, forming 2-3 layers and extending towards the periphery, at some points penetrating amongst the host cells. The myofibrils in some cases show evident aspects of lysis as a consequence of the appearance of lysosome-like vesicles. Lacking knowledge of a complete life cycle and/or molecular data precluded the conclusive identification of this species.