Fig. 13
From: Within-family plasticity of nervous system architecture in Syllidae (Annelida, Errantia)
Overview of the anterior nervous system and associated lobes of the Exogoninae. Both Exogoninae have a pair of dorsal lobes consisting of somata of the brain, reaching inside the anterior segments and a pair of nuchal lobes, consisting of support cells of the nuchal organ, which reach the second chaetiger. Four clusters of somata are present in the tentacular segment and first chaetigers of Prosphaerosyllis marmarae and one in Sphaerosyllis taylori. The palps are innervated by at least a main neurite bundle and a neurite bundle from the dorsal root of the circumoesophageal connective. A third neurite bundle reaches from the ventral root of the circumoesophageal connective inside the palps (uncertain in Prosphaerosyllis marmarae). A distinct circumoesophageal ganglion is not present. Somata are clustered on the ventral side of the circumoesophageal connective, fusing with the ganglion of the first chaetiger. Abbreviations: drcc – dorsal circumoesophageal connective; vrcc – ventral circumoesophageal connective