Amphicteis ninonae can be up to 75 mm long. It can be found in the Norwegian Sea, Barents Sea and around Svalbard at depths between 100 and 1000 meters.
Norwegian Sea, 68o00’N 10o00’E, 930–1010 m.
Measurements: Up to 75 mm long.
Number of thoracic chaetigers, excluding paleae: 17
Number of thoracic uncinigers: 14
Number of abdominal uncinigers: 15
Prostomium: With longitudinal ridges and transverse nuchal grooves; eyespots absent.
Mouth tentacles: Smooth.
Branchiae: Four pairs of branchiae in two groups separated by a distance equal to one branchial base diameter; the four branchiae in each group arranged in rhomboid pattern.
Paleae: Long and stout with curved tips; dark brown in colour; 8–16 chaetae on each side.
Special features: All abdominal segments with rudimentary notopodia.
Pygidium: With two long lateral cirri.
Tube: Thin layer of organic secretion covered by thick layer of mud.
Norwegian Sea, Barents Sea, Svalbard; 100–1000 m (deep in Norwegian Sea, Shallow in Barents Sea and Svalbard).
Amphicteis midas, wich is similar to Amphicteis ninonae in having stout paleae with curved tips, might occur in Norway. It can be differentiated from A. ninonae by the colour of the paleae, light yellow compared to dark brown in A. ninonae and number of paleal chaeta, usually less than 10 compared to usually more than 10 in A. ninonae. Amphicteis midas has a southern (English Channel), shallow (20 m) distribution while A. ninonae is distributed from the Norwegian Sea and into the Arctic Ocean in deeper waters.
Jirkov IA (2001). [Polychaeta of the Arctic Ocean] (In Russian). Polikhety severnogo Ledovitogo Okeana. Yanus-K Press. Moscow, 632 pp.
Parapar J, Helgason GV, Jirkov I, Moreira J (2011). Taxonomy and distribution of the genus Amphicteis (Polychaeta: Ampharetidae) collected by the BIOICE project in Icelandic waters. Journal of Natural History 45(23-24): 1477-1499. https://doi.org/10.1080/00222933.2011.558640
Personal observations, Alvestad T.