Morphologic and molecular characteristics of Sarcocystis atraii n. sp. (Apicomplexa: Sarcocystidae) infecting the common coot (Fulica atra) from Egypt.

A single morphologic type of Sarcocystis cysts found in two out of 43 examined common coots, Fulica atra, is considered to represent a new species for which the name Sarcocystis atraii n. sp. is proposed and its description is provided. Coots were hunted from the vicinity of Brolos Lake located at KafrElsheikh province, Egypt. The structural morphology of the revealed sarcocysts was described using light and transmission electron microscopy. Sarcocysts were found in the leg and thigh muscles. The cysts were microscopic and measured 165-850 μm in length × 50-85 μm in width. Histologically; the sarcocyst wall was wavy and had minute undulations. Ultrastructurally, it measured 1-3 μm in thickness and possessed many mushroom-like villar protrusions sometimes originating from other mushroom-like villar protrusions that measured approximately 0.5-2 μm in length and up to 2 μm in width, with the presence of electron dense ground substance of 300 nm to 1 μm thick. The bradyzoites were elongated, banana-shaped and measured 7.5-14 × 1.5-2.5 μm, with centrally or terminally located nuclei. The ultrastructural features of the cyst wall belonged to type 24. On the basis of sequencing and phylogenic analyses for 18S rRNA , 28S rRNA genes and ITS-1 region; S. atraii n. sp. is considered a genetically distinct species, being most closely related to avian Sarcocystis spp. whose definitive hosts are predatory mammals.