Laonice petersenae Radashevsky & Da Cunha Lana, 2009

Prostomium blunt, anteriorly truncate or rounded, anterior margin with entire anterior margin. Lateral horns absent. Caruncle present, continuing back to chaetiger 25–26 (shorter in small individuals). Occipital antenna present. Nuchal organ long, extending back more than one segment, extending posteriorly to chaetiger 25–26 (u-shaped ciliary bands on either side of caruncle). Eyes present; 4 eyes. 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 (3 in juveniles with fewer than 60 chaetigers). Dorsal branchiae absent from many median and posterior chaetigers (up to 34 pairs), last present on chaetiger 34. Dorsal branchiae continuous. Dorsal branchiae free and separate from notopodial lamellae throughout, all simple. First branchiae without process at base on anterior face. Dorsal branchiae longest on median chaetigers, decreasing in length anteriorly and posteriorly (full size from chaetigers 4–6 and decreasing in size posteriorly). Accessory branchiae arising from posterior part of notopodium absent. Ventral branchiae absent. Chaetiger 3 without filament at base of branchiae. Dorsal crests absent. Ventral crests absent. Chaetiger 1 notopodium present. Chaetiger 1 notochaetae present. Neuropodial lobe of chaetiger 2 rounded, approximately symmetrical. Neuropodial lobes of posterior chaetigers a single lobe. Interparapodial pouches present. Interparapodial pouches on chaetigers 3–17 (through to end of body, anterior position weakly correlated with body size). Chaetigers 2–4 similar, not strongly differentiated. Chaetiger 5 unmodified, similar to subsequent chaetigers. Posterior modified notochaetae absent. Notopodial hooded hooks absent. Neurochaetae of chaetiger 1 simple capillaries similar to those of subsequent chaetigers. Neuropodial hooded hooks present, first present on chaetiger 16–36 (up to 10 in a series). Neuropodial hooded hooks with accessory tooth or teeth above the main fang, 2 accessory teeth (tridentate). Shaft of neuropodial hooded hooks of constant thickness, lacking a constriction. Neuropodial sabre chaetae present, in ventral-most positions, first on chaetiger(s) 1–2 per chaetiger. Neuropodial spines absent. Embedded bunches of notopodial needle chaetae absent. Pygidium with one pair of short ventral cirri and up to four pairs of dorsal cirri arranged in two vertical rows on sides of terminal anus.

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:
Radashevsky, V.I., and Lana, P.C. 2009. Laonice (Annelida: Spionidae) from South and Central America. Zoosymposia 2: 265-295.