Pneumodermopsis paucidens

(Boas, 1886)

Described form occurring in the area (Van der Spoel et al., 1997): Pneumodermopsis paucidens (Boas, 1886) forma paucidens (Boas, 1886)

Description
A relatively small, naked pelagic snail; the visceral mass is seen through the body wall. Gills are less developed; the lateral gill is extremely short. A posterior gill is absent. The posterior footlobe is short. In young specimens, the footlobes are of equal size, but with age the posterior lobe rapidly lengthens. Median arm with 5 suckers, the top one is the largest, the two lower pairs are small and attached to long stalks [P.p.paucidens-arms]. Ten to welve suckers implanted on the buccal wall. [P.p.paucidens-or]. The penis is armed with a chitinous style.
Radula formula: 2-1-2, the median tooth is bicuspoid without central cusp [P.p.paucidens-r]. The number of transverse rows varies between 12 and 22. The few hooks, only 6 at each side, are short and broad.
A description of juveniles is not available; P.p.paucidens-j, juvenile.

Colour
The skin with greyish chromatophores. Pigmentation, in the larger specimens usually consists of thickly spotted dark chromatophores, occurring all over the animal except for the wings.

Size
Maximum body length 5 mm.

Depth range
Epi- to mesopelagic.

Ecology
P. paucidens lives in all oceans in shallow and deep water layers; it is a good swimmer that hunts shelled pteropods as food.

Distribution in the North Sea
Northern North Sea, Skagerrak.

World distribution
Atlantic Ocean between 65°N and 30°S, with the greatest population density between 65°N and 35°N; abundant in the Mediterranean; few records from the Indian Ocean (Arabian Sea and near Madagascar); uncertain identifications from the Pacific based on immature specimens.

[After Van der Spoel et al., 1997]