Two new Leptosomatidae species are described: Deontostoma conicum sp. nov., characterized by two conical odontia and transversal striae on the distal end of the gubernaculum — and Deontostoma duanei sp. nov., characterized by laterally directed odontia, specific measurements and gubernaculum morphology. Additional information is given on Deontostoma antarcticum (Linstow, 1892) and Deontostoma campbelli (Ditlevsen, 1921).