Six new species of the genus Molgolaimus Ditlevsen, 1921 are described from the Indian Ocean. Molgolaimus abyssorum n. sp. is characterised by a small body (L = 287-370 µm), amphids close to the anterior end (2-3 µm behind the anterior end), short (2 x abd) curved spicules and absense of pre-cloacal supplements.Molgolaimus tyroi n. sp. is characterised by a small body size (L = 225-290 µm), amphids close the anterior end (2 µm behind anterior), long thin spicules curved twice and one or two pre-cloacal supplements. Molgolaimus gazii n. sp. is characterised by narrow anterior end with the head region slightly offset, wide amphids (70% cbd) located at 2.6-3.0 x hd behind the anterior end, thin, long spicules with anterior one third parallel to the body axis and posterior two thirds of its lenght curved. Molgolaimus sabakii n. sp. is characterised by narrow anterior end, sexual dimorphism in size of amphids [wide amphids in males (70-80% cbd), smaller ones in females (55% cbd)] located at 17-20 µm (3.4-4.0 x hd) behind the anterior end, thin long spicules which have anterior half parallel to the body axis and the posterior half curved and two ventral pre-cloacal supplements located within the spicule region. Molgolaimus kiwayui n. sp. is characterised by head region off set by a constriction, amphids located close to anterior end (1.0-1.5 x hd behind the anterior end), short slightly curved spicules with capitulum.Molgolaimus tanai n. sp. is characterised by cephalic setae (2-3 µm long) located at 5-6 µm behind the anterior end, amphids located at 7-9 µm behind the anterior end, long slender spicules (3.8-5.1 abd long) and a complex gubernaculum with lateral pieces. A key to the species of Molgolaimus is provided. |