Niconpictus Kinberg, 1865.

https://www.marinespecies.org/polychaeta/aphia.php?p=taxdetails&id=173735.

Pettibone (1971).

Maxillary ring paragnaths and papillae absent; neuropodial postchaetal lobe present; dorsal notopodial ligule commences chaetiger 3; dorsal notopodial ligule not markedly reduced on posterior chaetigers; oral ring paragnaths absent; notochaetae homogomph falcigers absent (minimal diagnosis; secondary diagnosis not attained).

Palpophore barrel-shaped, approximately equal width from base to palpostyle (not overly large compared with palpostyle). Palpophore surface with a single transverse groove (palpophores well developed). Eyes present, or absent. Tentacular belt greater than length of chaetiger 1.

Jaws with dentate cutting edge.

Maxillary ring of pharynx with papillae and paragnaths absent. Oral ring papillae and paragnaths absent.

Dorsal notopodial ligule present, or absent; not markedly elongate on posterior chaetigers; not markedly broader on posterior chaetigers; not markedly reduced on posterior chaetigers. Prechaetal notopodial lobe present, or absent; smaller than dorsal notopodial ligule on anterior chaetigers, usually reduced or absent posteriorly; restricted to a limited number of anterior chaetigers. Notopodial acicular process absent. Dorsal cirrus not sub-terminally attached to dorsal notopodial ligule on posterior chaetigers; not terminally attached to dorsal notopodial ligule on posterior chaetigers; not terminally attached throughout all chaetigers.

Neuropodial prechaetal lobe absent. Neuropodial postchaetal lobe present; projecting beyond end of the acicular ligule; present throughout all chaetigers, or restricted to anterior chaetigers; digitiform. Ventral neuropodial ligule of anterior chaetigers present. Ventral neuropodial ligule of anterior chaetigers approx. as long as acicular neuropodial ligule. Ventral neuropodial ligule on posterior chaetigers present. Ventral neuropodial ligule on posterior chaetigers similar to length of acicular neuropodial ligule.

Notoaciculae on chaetigers 1 and 2 absent. Notochaetae: homogomph spinigers present. Neurochaetae dorsal fascicle: heterogomph spinigers present, or absent; homogomph spinigers present; heterogomph falcigers in anterior chaetigers present, or absent; on posterior chaetigers present, or absent; blades serrated; simple chaetae (fused falcigers) present, or absent; homogomph falcigers in anterior chaetigers present, or absent. Neurochaetae ventral fascicle: sesquigomph falcigers present, or absent; heterogomph spinigers present, or absent; homogomph spinigers present, or absent; heterogomph falcigers present; anterior chaetigers heterogomph falcigers with long blades absent; anterior chaetigers heterogomph falcigers with extra-long blades present; anterior chaetigers heterogomph falcigers with short blades absent; posterior chaetigers heterogomph falcigers with long blades present, or absent; posterior chaetigers heterogomph falcigers with extra-long blades present, or absent; posterior chaetigers heterogomph falcigers with short blades absent; heterogomph falcigers blade with recurved terminal tooth and distinct tendon, or lacking distinct tendon on terminal tooth; homogomph falcigers in anterior chaetigers present, or absent.

Pygidium bilobate. Anal cirri form cirriform or conical.

Nicon is not a species-rich genus: of the 700+ species of Nereididae, only ten belong to the genus Nicon and those ten species are from diverse habitats and widespread regions (Read and Fauchald 2023). Nicon species exhibit more morphologically diversity than seen in many genera of Nereididae and with only a single species included in the most recent study (Wang et al. 2021), both their phylogenetic placement within Nereididae and their monophyly are doubtful.

The two most recent studies describing new Nicon species, de León-González and Trovant (2013) and Wang et al. (2021), both also provided keys to the then-known species.