The family Dorylaimidae and the subfamilies Amphidorylaiminae, Prodorylaiminae, Dorylaiminae and Laimydorinae are characterized. 19 genera are defined and 224 valid species enumerated and presented in form of keys. Four new genera, Apodorylaimus (supplements, 5-8 arranged in pairs), Protodorylaimus (prerectum excessively long (15-25 anal diameters), slender body), Crocodorylaimus (conspicuous yellowish spots present around the basis of spear) and Halodorylaimus (amphidial aperture smaller than usual, haline forms) are proposed. Seven new species are described: Apodorylaimus bini, Dorylaimus numidicus, Dorylaimus fodori, Crocodorylaimus aequatorialis, Crocodorylaimus dimorphus, Mesodorylaimus kittenbergeri and Calodorylaimus densus. A. bini sp. nov. from India can be distinguished from A. congonensis by the longer body (1.2 - 1.7 mm), longer spear (24-26 mu m), longer and more sharply pointed tail (18-22 anal diameters) and, more numerous supplements (8) lying before spicula. D. numidicus sp. nov. from Algeria differs from D. afghanicus in having fewer supplements (22-27). D. fodori sp. nov. from India, differs from D. afghanicus in having a shorter and thinner spear (40-42 mu m; 5 mu m), a lower guiding ring and less numerous supplements. C. aequatorialis sp. nov. from Ecuador differs from C. dadayi in having a longer body (2.0-2.2 mm), longer spear (17-19 mu m), wider head (12 mu m), larger spermatozoa (15-17 mu m, one-third body width), longer spicula (54-58 mu m), more numerous supplements (17-22) and large flat subterminal blister. C. dimorphus sp. nov. from Vietnam can be distinguished from the smaller species of the genus in showing a sexual dimorphism in the length of spear and in having supplements just begining at the proximal end of the spicula. M. kittenbergeri sp. nov. from Kenya is distinguished from all known species of the genus by its short and characteristic female tail (dorsally curved digitate process). C. densus sp. nov. from India is easily distinguished from other members of the genus by the greater number (31) and arrangement of supplements. Several new combinations are proposed.
