Syllidae Grube, 1850

Barroso, Rômulo, Paiva, Paulo Cesar De, Nogueira, João Miguel De Matos & Fukuda, Marcelo Veronesi, 2017, Deep sea Syllidae (Annelida, Phyllodocida) from Southwestern Atlantic, Zootaxa 4221 (4), pp. 401-430 : 402

Family Syllidae Grube, 1850

Type genus. Syllis Savigny in Lamarck, 1818 .

Diagnosis. Small sized polychaetes, with nearly cylindrical to strongly dorso-ventrally flattened bodies. Palps well developed, from completely free from each other to completely fused. Prostomium typically with 2 pairs of eyes, sometimes also with 1 pair of anterior eyespots, and 3 antennae. Peristomium with 1–2 pairs of peristomial cirri. Smooth to articulated dorsal cirri, usually longer on anterior chaetigers; ventral cirri usually present, shorter than dorsal cirri. Compound chaetae as falcigers; modified falcigers frequently present as spiniger-like chaetae or, more rarely, secondarily simple due to loss of blade or fusion to shaft; falciger blades unidentate or bidentate, distal teeth of variable sizes. Dorsal and ventral simple chaetae usually present, at least on posterior chaetigers. One to many aciculae of variable morphologies per parapodium, typically progressively fewer and stouter posteriorwards. Pygidium with 1 pair of anal cirri, usually longer than posterior dorsal cirri. Straight to sinuous pharynx on anterior segments, usually with anterior margin surrounded by papillae and central tooth and/or trepan; some species with unarmed pharynx; pharynx followed by muscular proventricle of variable size. Reproduction by epigamy or schizogamy, sometimes with incubation of eggs and embryos; a few species viviparous.