Sosane wahrbergi
Sosane wahrbergi is a very small species, only up to 4 mm long. It can be found along the entire Norwegian coast at depths between 20 and 300 meters.
Type locality
Koster Islands, Sweden, 20–80.
Key characters
Measurements: Up to 4 mm long.
Number of thoracic chaetigers, excluding paleae: 12
Number of thoracic uncinigers: 9
Number of abdominal uncinigers: 12
Prostomium: Trilobed; one pair of eyespots.
Mouth tentacles: Smooth.
Branchiae: Three pairs of branchia in two widely separated groups; branchiae arranged in triangles.
Paleae: Small with filiform tips; 15–20 chaetae on each side.
Special features: 12th pair of thoracic notopodia elevated and laterally enlarged; chaetae usually crossing mid-dorsally.
Pygidium: With long lateral cirri.
Tube: Thin layer of organic secretion incrusted with mud.
Distribution
Entire Norwegian coast; 20–300 m.
Similar species
Sosane bathyalis and Sosane wahrbergi are morphologically very similar, particular since fixed specimens of S. wahrbergi quite often miss eyes. Sosane bathyalis are generally smaller than S. wahrbergi and occur much deeper.
Sources
Holthe T (1986a). Polychaeta Terebellomorpha. Marine Invertebrates of Scandinavia 7: 1-192.
Personal observations, Alvestad T.