Cheilonereis cyclurus

Prostomium with entire anterior margin. Longest tentacular cirri extend back to chaetiger 4–8. Maxillary ring divided into discrete Areas. Maxillary ring of pharynx with paragnaths; paragnaths arranged in discrete areas. Area I paragnaths present; conical paragnaths present; 2–19 conical paragnaths on Area I; minute rod-like paragnaths in a compact cluster absent; II present; II conical paragnaths present; 14–37 conical paragnaths on Area II; II minute rod-like paragnaths in a compact cluster absent; pectinate paragnaths absent; III present; conical paragnaths present; 8–30 paragnaths (distinct lateral groups usually absent); minute rod-like paragnaths in a compact cluster absent; pectinate paragnaths absent; IV present; conical paragnaths present; 17–48 conical paragnaths; minute rod-like paragnaths in a compact cluster absent; smooth bar-like paragnaths absent; pectinate paragnaths absent. Oral ring papillae absent. Oral ring paragnaths present. Area V and VI present as distinct groups. Area V conical paragnaths absent; VI present; arranged in a roughly circular group; cones present; 7–14 conical paragnaths; smooth bars absent; pectinate rows absent; VII-VIII present; conical paragnaths present; 117–306; Band of conical paragnaths on Areas VII-VIII discontinuous, present only as a ventral band; pectinate paragnaths absent; arranged in one or more irregular lines forming a continuous band; VII-VIII paragnaths differentiated into an anterior band of paragnaths similar in size to elsewhere on the proboscis, and a separate band of minute paragnaths. Transverse dorsal lamellae absent. Dorsal notopodial ligule markedly elongate on posterior chaetigers. Markedly broader on posterior chaetigers. Dorsal notopodial ligule not markedly reduced on posterior chaetigers. Prechaetal notopodial lobe present. Dorsal cirrus not terminally attached to dorsal notopodial ligule on posterior chaetigers. Dorsal cirrus length about 1.5 times ventral notopodial ligule at chaetiger 10-20. Neuropodial postchaetal lobe present, at least on some anterior chaetigers. Ventral neuropodial ligule on posterior chaetigers similar to length of acicular neuropodial ligule (although entire neuropodium is reduced in size compared with notopodium on posterior chaetigers). Ventral cirri single.

Unless stated otherwise in the below description, the following character states are implicit for all Nereididae species: 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.

Distinguished from other members of the genus by: Area VII-VIII paragnaths differentiated into an anterior band of paragnaths similar in size to elsewhere on the proboscis, and a separate band of minute paragnaths

North America, Pacific coast.