Lohmann, 1896
Description
Trunk in dorsal view rectangular, but narrowed in the middle, the anterior part rounded. Two large triangular cuticular appendices posteriorly.
Trunk in lateral view dorso-ventrally compressed; the part anterior of the proximal end of the oesophagus, is clearly curved downwards. Mouth with large upper lip; the pharynx is small.
Endostyle narrow and strongly curved; the pharyngial glands are situated directly behind the endostyle and point backwards to the left side of the animal, without touching the spiracles. Spiracles small and round.
The digestive tract is compact and small compared with the length of the body. Intestine situated right behind the stomach; the rectum is almost vertical, ending in an anus that is located at the left side of the body.
Genital cavity very large. In young specimens, the gonads are touching the posterior end of the digestive tract; in mature specimens, the testis is trapezoidal and laterally encircled by the ovary in a string.
The tail has narrow muscle bands; in the rear third of the tail, at each side of the chord, there are two sometimes difficult to distinguish elongated amphicordial glands. The rear end of the tail is insiced.
Size
Trunk length 1.25 mm, tail length 1.75-2.0 mm.
Ecology
F. venusta is a very eurytherm thermophilic species.
Depth range
Epipelagic
Distribution in the North Sea
North Sea
World distribution
Recorded from the Antarctic, Norwegian Sea, west of Ireland, Mediterranean, Gulf of Aden, NW Arabian Sea.
[Fenaux, 1967]