Exogone Örsted, 1845

Fukuda, Marcelo Veronesi & Nogueira, João Miguel De Matos, 2014, A new species of Exogone (Syllidae: Exogoninae) from off the state of São Paulo (south-east Brazil), Memoirs of Museum Victoria 71, pp. 79-84 : 80

Genus Exogone Örsted, 1845

Type species. Exogone naidina Örsted, 1845 .

Diagnosis. Relatively small, thin and slender bodies. Palps well developed, completely fused or with terminal notch. Prostomium ovate, with 2 pairs of eyes in trapezoidal arrangement and, sometimes, 1 pair of anterior eyespots; 3 smooth antennae, all short and ovate, or at least median antenna elongate, digitiform. Peristomium with 1 pair of peristomial cirri. Dorsal cirri present on all chaetigers or absent on chaetiger 2. Peristomial, dorsal and ventral cirri short, papilliform to ovate. Compound chaetae with subdistally inflated and spinulated shafts; in some species, shafts with conspicuous subdistal triangular enlargement (‘triangular process’) on spiniger-like chaetae of a few anterior parapodia. Blades of falcigers usually spinulated, bidentate, distal tooth smaller than subdistal one; dorsalmost compound chaetae frequently with long and slender spiniger-like blades, with short spinulation. In some species, compound chaetae secondarily simple by fusion of shaft and blade, or by loss of blade. Dorsal simple chaetae present from anterior body, usually sigmoid, progressively stouter posteriorwards; dorsal simple chaetae bayonet-like in some species. Ventral simple chaetae usually present only on posteriormost chaetigers, bidentate, distal tooth smaller than subdistal one. Aciculae distally inflated, apparently hollow, with slightly bent tip. Pygidium with one pair of anal cirri, usually longer than dorsal cirri along body ( San Martín, 2005).