“Syndesmis obhoriensis” new species : an endoparasite turbellarian (Rhabdocoela : Umagillidae)‎ of the sea-urchin “Echinothrix diadema” in the red sea (Jeddah)‎

الملخص EN

A new endoparasitic Turbellarian “Syndesmis obhoriensis" nov.

sp.

was collected for the first time from the coelomic cavity of the sea-urchin Echinothrix diadema.

The host was living in the shallow water of Obhor Creek, north Jeddah (Red Sea) on the sandy bottom from a depth varying from 3 to 5 meters.

It is related to the family Umagilleidae and the genus Syndesmis.

The worm is considered to be a new species for the following main reasons : 1.The worm is cylindrical in shape, pale white in color and its length reaches about 4 mm.

2.The intestine is saccate having a syncytial structure.

3.The epidermal layer is syncytial in structure.

4.The uterus extends anteriorly from the female antrum and ends a little distance after the vitallaria and its anterior end is attached to the oval egg capsule, continued posteriorly as a long much coiled multi-filamenton whip in the form of 8.

5.The vitellaria have six finger-like branches on each side.

6.Cement gland cells are fully occupying the last third part of the body.

7.Seminal vesicle is rounded.