Additional file 4 of Within-family plasticity of nervous system architecture in Syllidae (Annelida, Errantia)

Additional file 4 Figure S4. Anterior nervous system of Syllidae and Nereididae as described previously. The neuropil of the brain is connected to the ventral nerve cord via the circumoesophageal connective. Both the dorsal and the ventral root of the circumoesophageal connective form a dorsal and a ventral commissure within the brain. The dorsal commissure of the dorsal root of the circumoesophageal connective (dcdr) forms nerve tracts that reach toward the posterior ganglia, which are involved in the innervation of the nuchal organ. Smaller commissures were omitted. A: Syllidae redrawn after [32] and [25]. The dcdr sends fibres to the lateral and median antennae. A pair of dorsal ganglia lies above each dorsal root of the circumoesophageal connection. It is innervated by fibres originating from the ventral side of the neuropil of the brain. A cluster of globuli cells lies at the beginning of each palp. The palps are innervated by root 6 coming from the ventral commissure the ventral root of the circumoesophageal connective and root 9 coming from the dorsal root of the circumoesophageal connective. Two pairs of stomatogastric nerves emanate from the ventral commissure of the ventral root of the circumoesophageal connective and one from the circumoesophageal connective where dorsal and ventral root fuse. B: Nereididae redrawn after [10, 11, 25, 72]. The dcdr and the ventral commissure of the dorsal root of the circumoesophageal connective (vcdr) send fibres to the lateral antennae. At least one pair of mushroom bodies (depending on species, rose, dotted line) lies above the neuropil of the brain. Behind them, at the latteral frontal margins of the prostomium lies the Langdons organ (dotted lines). Seven nerves innervate the palps. Five pairs of stomatogastric nerves innervate the pharynx. Abbreviations: cc – circumoesophageal connective; dcdr – dorsal commissure of drcc; dcs – dorsal cluster of somata (dorsal ganglion); dcvr – dorsal commissure of vrcc; drcc – dorsal root of the circumoesophageal connective; gl – ganglion of globuli-like cells; lan – lateral antenna; man – median antenna; nn – nuchal nerve; pgl – posterior ganglion; pn1–12 – palp nerves; stgn 1–3 – stomatogastric nerves 1–3; tcn – neurite bundle innervating tentacular cirri; vcdr – ventral commissure of drcc; vcvr – ventral commissure of vrcc; vrcc – ventral root of the circumoesophageal connective.