Laonice japonica (Moore, 1907)

Prostomium blunt, anteriorly truncate or rounded, anterior margin with entire anterior margin. Caruncle present, continuing back to chaetiger a low, narrow ridge continues along the dorsum. Occipital antenna present. Nuchal organ short, at most one segment long. Eyes present; 2 eyes (large, conspicuous, reddish-brown, crescentic; anterior to each is a curved series of small pigment specks). 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 3. Dorsal branchiae absent from many median and posterior chaetigers, last present on chaetiger 42. First branchiae without process at base on anterior face. Accessory branchiae arising from posterior part of notopodium absent. Ventral branchiae absent. Chaetiger 3 without filament at base of branchiae. Dorsal crests present; first dorsal crest present on chaetiger 38. Ventral crests absent. Chaetiger 1 notopodium present. Anterior setigers with 2 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 4. 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 41. Neuropodial hooded hooks with accessory tooth or teeth above the main fang, 1 accessory tooth (bidentate) (in side view). Shaft of neuropodial hooded hooks of constant thickness, lacking a constriction. Neuropodial spines absent. Embedded bunches of notopodial needle chaetae absent. Pygidium unknown.

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:
Moore, J.P. 1907. Descriptions of new species of spioniform annelids. Proceedings of the Academy of Natural Sciences of Philadelphia. 59: 195-207.