19 species of ciliates were found in interstitial biotopes of the Fulda Headwater. Two of these were new: Haplocaulus hengsti, n.sp. and Epistylis rotti, n.sp. (Peritrichida). The number of ciliate species decreases from the surface down so deeper layers; in a depth of 50 cm, only three species were found: Haplocaulus hengsti and Epistylis rotti and another small ciliate Trachelophyllum apiculatum. There was little detritus in this layer, and so, the abundance of the ciliates was low. On the other hand, there is little predation in deeper layers of stygorhithral sand and gravel. Small, long and thin ciliates seem so be specially adapted to life in deeper regions of the stygornithral Stygorhithral ciliates are related to custygal species with respect to several characteristics of their morphology and general biology.