Malacoceros jirkovi Sirkorski, 1992

Prostomium blunt, anteriorly truncate or rounded, anterior margin with entire anterior margin. Lateral horns present. Caruncle present, continuing back to chaetiger 2. Occipital antenna absent. Nuchal organ short, at most one segment long. Eyes present; 2 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 1. 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. 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 absent. 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 26. Neuropodial hooded hooks with accessory tooth or teeth above the main fang, 1 accessory tooth (bidentate) or 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) 6. 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.