Three new species (Psammonema ovisetosum gen. et sp. n., Pseudochromadora coomansi sp. n.and Pseudochromadora buccobulbosa sp. n.; including all juvenile stages) belonging to a known and to a new genus of the family Desmodoridae (Nematoda, Desmodoroidea) were found in sandy sediments of the intertidal zone in front of the estuarine mangroves of Gazi, Kenya. Psammonema gen. n. differs from Pseudochromadora Daday, 1889 in shape and number of somatic setae in pharyngeal region, in position and shape of lateral alae, and in the anterior position of the amphids on the head capsule. Comments are given on the ecto-symbiotic organisms, feeding habits of the species and on the ontogenetic transformations of some morphological characters.