Abstract
Sediment samples collected at low tide from various localities in the Jubail Marine Wildlife Sanctuary, the Arabian Gulf, Saudi Arabia during 1996-1997 have revealed 22 species in 4 genera (Tracheloraphis, Kentrophoros, Avelia and Geleia) of the interstitial ciliate order Karyorelictida. Of these, 19 species are new records for the fauna of Saudi Arabia, and the Arabian Gulf at large. The distribution of each species has been compared to those in similar habitats worldwide. Photographs of protargol impregnated cells, kinety numbers and brosse rows for each Tracheloraphis species are given.