Sarcocystis schneideri n. sp. (Sarcocystidae) infecting the barber skink Eumeces schneideri schneideri (Scincidae) Daudin, 1802. A light and ultrastructural study.

The current study provides the first record of infection with Sarcocystis species in the barber skink Eumeces schneideri schneideri (Scincidae) captured from the north region of Egypt around the cities of El-Hamam and Al-Dabaa, Mersa Matruh Governorate, Egypt. Morphology of the parasite cysts was described using light and transmission electron microscopy. Five out of 80 (6.25%) of the examined skinks were found to be infected. The infection was recorded firstly by light microscopy as spindle-shaped cysts embedded in the muscle tissue. The cysts were microscopic and measured 250-900 μm in length × 50-100 μm in width (mean, 575 × 75 μm). The validity of this species was confirmed by means of ultrastructural characteristics of the primary cyst wall (0.28 μm thick) which revealed the presence of irregularly shaped crowded and osmiophilic knob-like projections underlined by a thin layer of ground substance measuring 0.15-0.17 μm (mean, 0.16 μm). This layer consisted mainly of fine, dense homogenous granules enclosing the developing metrocytes and merozoites that usually contain nearly all the structures of the apical complex and fill the interior cavity of the cyst. Several septa derived from the ground substance divided the cyst into compartments. The merozoites were banana-shaped and measured 3-5 μm in length and 1.5-2.5 in width with centrally or posteriorly located nuclei. The morphological and morphometric data obtained during study were compared with those recorded previously from organisms within the Scincidae family. It was observed that this parasite possessed some distinguishing characteristics from the comparable species, which should be considered as a new species of the Sarcocystis genus, and the proposed name was Sarcocystis schneideri n. sp. with new host and locality records in Egypt.