Laonice norgensis Sikorski, 2003

Prostomium blunt, anteriorly truncate or rounded, anterior margin with entire anterior margin or bifid, with anterior margin indented (small apical incision in some specimens). Lateral horns absent. Caruncle present, continuing back to chaetiger 15–33 (prostomium not fused with peristomium; narrowing graduually from anterior margin to middle and then abruptly narrowing posteriorly into caruncle). Occipital antenna present (finger-like, erect, as long as setiger 1, at posterior end of prostomium behind eyespots). Nuchal organ long, extending back more than one segment, extending posteriorly to chaetiger 15–33 (correlated with size). Eyes present; 2–4 eyes (brown or reddish, posterior pair small or large, anterior pair pair, multiple positions possible, see paper). Palps simple, lacking basal sheath. Dorsal ridge connecting bases of branchiae on chaetiger 1 absent. Prominent dorsal collar on setiger 2 absent. Dorsal branchiae present, first present on chaetiger 2. Dorsal branchiae continue to near posterior end of body. Dorsal branchiae continuous. Dorsal branchiae free and separate from notopodial lamellae throughout, all simple. First branchiae without process at base on anterior face. Branchiae absent only from final 15–36 chaetigers according to Sikorski 2003, this character size dependent. Accessory branchiae arising from posterior part of notopodium absent. Ventral branchiae absent. Chaetiger 3 without filament at base of branchiae. Dorsal crests present (every setiger with 2 transverse membranes, 1 connecting bases of notopodial lamellae, another following the anterior border of the setiger); first dorsal crest present on chaetiger 7 (interrupted only by nuchal organs). Ventral crests absent. Chaetiger 1 notopodium present. Chaetiger 1 notochaetae present. Anterior setigers with 2–4 rows of chaetae. Neuropodial lobe of chaetiger 2 rounded, approximately symmetrical. Neuropodial lobes of posterior chaetigers a single lobe. Interparapodial pouches present. Interparapodial pouches on chaetigers 8–65 (started 8–17, on every setiger for 2–65 segments, the irregular until 9–21 setigers from pygidium). Chaetigers 2–4 similar, not strongly differentiated. Chaetiger 5 unmodified, similar to subsequent chaetigers. Posterior modified notochaetae absent. Neurochaetae of chaetiger 1 simple capillaries similar to those of subsequent chaetigers. Neuropodial hooded hooks present, first present on chaetiger 16–31 (starting with 4–12 per fasicle, increasing to 6–17). Neuropodial hooded hooks with accessory tooth or teeth above the main fang, 2 accessory teeth (tridentate) (bidentate in side view). Shaft of neuropodial hooded hooks of constant thickness, lacking a constriction. Neuropodial sabre chaetae present, in ventral-most positions, first on chaetiger(s) 9–18 (up to 4 per fascicle, decreasing to 1 in posterior part of body). Neuropodial spines absent. Embedded bunches of notopodial needle chaetae absent. Pygidium bears a pair of short and thick ventral cirri placed rather far apart (characteristic of all Laonice species) and up to 6 pairs of thread-like long dorsal cirri.

Description generated from: Wilson, RS & McDiarmid, H 2013. Spionidae (Polychaeta)- A DELTA database of genera, and Australian species. Version 2; originally published as In RS Wilson, PA Hutchings & CJ Glasby (eds) Polychaetes: An Interactive Identification Guide. CSIRO Publishing, Melbourne.

Additional references:
Sikorski, A.V. 2003. Laonice (Polychaeta, Spionidae) in the Arctic and the North Atlantic. Sarsia 88: 316-345.