Nectoneanthes Imajima 1972

Original diagnosis by Imajima (1972: 113): ''The body is long and attains to about 300 mm long. The prostomium is broader than long and has two short frontal antennae. The proboscis has chitinous paragnaths on all areas. Anterior parapodia have three notopodial ligules; all are slender digitiform and subequal. In median parapodia superior lobe of notopodium is much enlarged, and dorsal cirrus is deeply inserted between dorsal lobe and superior ligule. All notopodial and neuropodial setae are homogomph spinigers only.''

Diagnosis by Sato (2013: 3): "Prostomium with entire anterior margin, one pair of antennae, one pair of palps, two pairs of eyes. Eversible proboscis with conical paragnaths on both maxillary and oral rings. Four pairs of tentacular cirri. Parapodia of first two chaetigers sub-biramous, all following parapodia biramous. Sub-biramous parapodia with thin notoacicula and thick neuroacicula. Notopodia consisting of dorsal cirrus, dorsal ligule, prechaetal lobe and ventral ligule in biramous parapodia; notopodial dorsal ligule expanded with prominent ovoid lobe developing above dorsal cirrus in middle and posterior parapodia even in atokes. Neuropodia consisting of inferior lobe, postchaetal lobe, ventral ligule and ventral cirrus throughout; all neuropodial lobes and ligule slender and conical. Notochaetae homogomph or sesquigomph spinigers. Neurochaetae in both upper and lower fascicles consisting of homogomph or sesquigomph spinigers and heterogomph spinigers. Falcigers absent except for neurochaetae in juveniles."

Nectoneanthes is similar to Alitta and to Neanthes. Wilson (1988) placed Nectoneanthes, type species N oxypoda, as a synonym of genus Neanthes, whereas Bakken & Wilson (2005) placed it in Alitta, continuing the revival by Khlebovich (1996) of Alitta from synonymy with Neanthes. However Sato (2013) revived Nectoneanthes for N oxypoda and a new species, N. uchiwa. He stated the unique characters of Nectoneanthes were the absence of falcigers in adults, and the presence of an ovoid lobe above the dorsal cirrus in the middle and posterior parapodia even in atokes.