Nereididae

Prostomium with a narrow anterior and a wide posterior part (inverted T-shape) in most taxa; others with triangular or roughly diamond-shaped prostomia. Peristomium limited to lips. Paired frontal antennae present in almost all taxa. Palps ventral, tapering, articulated (but see Harper 1979: 95). Nuchal organs short ciliated grooves. Longitudinal muscles grouped in bundles; segmentation distinct. First segment indistinct with tentacular cirri only; four pairs of tentacular cirri present in most taxa; other taxa with two or three pairs. Both parapodial rami welldeveloped; notopodia shorter than neuropodia in most taxa. Dorsal and ventral cirri present. Gills and epidermal papillae absent. Paired pygidial cirri present. Lateral organs and dorsal cirrus organs not observed. Stomodaeum with axial, muscular eversible pharynx; terminal papillae absent; lateral jaws present. When everted outer surface of pharynx with either papillae or paragnaths or both in characteristic patterns in most taxa. Gular membrane absent; gut a straight tube. Metanephrida completely separated from ciliophagocytic organs; present in most segments. Circulatory system closed; heart body absent. Aciculae present. All chaetae compound; appendages joined to shafts by single ligaments. Appendages slender and tapering to fine tips, or bluntly falcate, sometimes dentate. (from Fauchald, K. & Rouse, G. W. (1997) Polychaete systematics: past and present. Zoologica Scripta, 26, 71-138.)

Notopodia distinct (rarelyreduced), usually with one or more flattened lobes,notochaetae compound falcigers and/or spinigers (rarelynotochaetae absent) (Glasby 1993: 1558). Another characteristicfeature of the nereidid is the inverted T-shapedprostomium; this is present in most taxa, small-bodiedspecies tend to have diamond-shaped prostomia withrounded corners. (from Fauchald, K. & Rouse, G. W. (1997) Polychaete systematics: past and present. Zoologica Scripta, 26, 71-138.)

The following characters are implicit in all contained Nereididae species descriptions unless stated otherwise:

Maxillary ring of pharynx without papillae. Maxillary ring divided into discrete Areas. Maxillary ring of pharynx with paragnaths; paragnaths arranged in discrete areas; Areas II, III and IV paragnaths not in regular comb-like rows (but may be arranged in irregular rows). Area I minute rod-like paragnaths in a compact cluster absent; II minute rod-like paragnaths in a compact cluster absent; pectinate paragnaths absent; minute rod-like paragnaths in a compact cluster absent; pectinate paragnaths absent; minute rod-like paragnaths in a compact cluster absent; smooth bar-like paragnaths absent; pectinate paragnaths absent. Oral ring papillae absent. Ring of oral ring paragnaths present as irregular rows, not crown-shaped. Smooth bars absent; pectinate rows absent; pectinate paragnaths absent; arranged in one or more irregular lines forming a continuous band; Area VII-VIII paragnaths similar in size, or irregular mix of large and small paragnaths in a single band. Transverse dorsal lamellae absent. Dorsal notopodial ligule not markedly elongate on posterior chaetigers. Not markedly broader on posterior chaetigers. Ventral cirri single.