Genus Odontosyllis Claparède, 1863

Type species: S yllis fulgurans Audouin & Milne Edwards, 1833, designated by Hartman (1959).

Diagnosis. Medium to large sized body. Prostomium with two pairs of eyes, occasionally also with one pair of anterior eyespots, and three antennae; palps free or fused only at bases. Nuchal organs as one pair of ciliated rows extending along posterior border of prostomium. Peristomium with two pairs of cirri and, usually, rounded occipital flap, covering at least posterior part of prostomium. Antennae, peristomial and dorsal cirri throughout smooth to irregularly wrinkled, usually distally tapering. Compound chaetae as uni- or bidentate falcigers. Pharynx usually short, central tooth absent, trepan with teeth directed backwards and, frequently, two lateral plates. Reproduction by epigamy; epigamous frequently bioluminescent.

Remarks. Odontosyllis brevichaetosa sp. nov. is the fifth known species of the genus occurring off the Brazilian coast, the others being O. guillermoi Fukuda & Nogueira, 2006, O. cf. fulgurans (Audouin & Milne Edwards, 1833) and O. guarauensis Fukuda, Nogueira, Paresque & San Martín 2013, all described from São Paulo, and O. aracaensis Fukuda, Nogueira, Paresque & San Martín 2013, described from São Paulo (southeastern Brazilian coast), but also occurring in Paraíba and Pernambuco (northeastern coast) (Fukuda & Nogueira 2006; Fukuda et al. 2013).