Protodrilus helgolandicus

Von Nordheim, 1983

Description:
Tentacles up to 500 µm long. Small so-called statocysts at base of each tentacle. Two round nuchal organs. No eyes. Two well-developed adhesive lobes, posteriorly broadened; a tiny median pygidial projection may occur between them. Head region with seven rings of cilia, which are dorsally interrupted except for rings 4 and 5. No ciliary rings on trunk segments, but numerous tufts of sensory cilia all over body. Weakly developed salivary glands up to segments 13 or 14 in females, up to segments 18 or 20 in mature males; in juveniles extending even further. Salivary glands of first 5-7 segments accompanied by brownish glands.
Male gonads from segment 10 posteriorly, female gonads mostly from segment 20 posteriorly. Lateral organs form continuous depressions from segment 6 to 9. Three pairs of spermioducts in segments 6-8. No oviducts.

Size:
Up to 10.5 mm for 55-65 segments.

Colour:
Opaque white appearance caused by epidermal glands with small granules, present throughout entire body except in summer during period of reproduction, when epidermal ornamentation is present only in anterior and posterior parts of the body. Bacillary glands on prostomium, in a ventral and ventrolateral row on each side of trunk, and scattered on dorsal side. Pharynx transparent or slightly dark.

Habitat:
Coarse sandy and shelly subtidal sediments, Amphioxus -sands.

Distribution:
North Sea (Helgoland), Skagerrak (west coast of Sweden, Gullmarfjord).

Remarks.
Damaged specimens smell like iodine.

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