New data on the morphology of Spinitectus oviflagellis Fourment, 1884 (Nematoda: Cystidicolidae) from the pyloric caeca of Macrourus berglax (Macrouridae) in the eastern Greenland Sea.

Specimens of a little-known nematode, Spinitectus oviflagellis Fourment, 1884, the type-species of Spinitectus Fourment, 1884, were collected mainly from the pyloric caeca of a marine deep-water fish, the onion-eye grenadier Macrourus berglax Lacépède (a new host record), in the eastern Greenland Sea, North Atlantic Ocean. Studies using light and scanning electron microscopy revealed some taxonomically important, previously unreported features of S. oviflagellis, such as the detailed structure of the cephalic end, the position of the excretory pore and the presence of ventral pre-anal cuticular ridges (area rugosa) in the male, which indicated a certain degree of intraspecific biometrical variability in this species. S. oviflagellis is compared with similar congeneric species parasitising marine fishes.