Cheilonereis

Prostomium with entire anterior margin. Maxillary ring divided into discrete Areas. Maxillary ring of pharynx with paragnaths; paragnaths arranged in discrete areas. Area I paragnaths present; conical paragnaths present; minute rod-like paragnaths in a compact cluster absent; II present; II conical paragnaths present; II minute rod-like paragnaths in a compact cluster absent; pectinate paragnaths absent; III present; IV present; conical paragnaths present; 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; smooth bars absent; pectinate rows absent; VII-VIII present; conical paragnaths present; Band of conical paragnaths on Areas VII-VIII discontinuous, present only as a ventral band; arranged in isolated patches; 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 (though not confirmed for C. peristomialis). 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. Neuropodial postchaetal lobe absent, or present, at least on some anterior chaetigers. Ventral neuropodial ligule on posterior chaetigers similar to length of acicular neuropodial ligule. Ventral cirri single. Notopodial homogomph spinigers present; sesquigomph spinigers absent. Notopodial homogomph falcigers present. Notopodial homogomph falcigers articulated throughout. Notopodial homogomph falcigers multidentate, with 2 or more small lateral teeth, first and subsequent lateral teeth much smaller than terminal tooth. Neuropodial dorsal fascicle fused falcigers absent.

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 Nereididae genera by: Ventral peristomial flap present, covering Area VII-VIII when proboscis everted; Oral ring papillae absent