Table 4 Compilation of features of the nervous system in representatives of different annelid groups and Lobatocerebrum riegeri n. sp
ANNELIDA | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
PREVIOUS “PROBLEMATICA”, now ANNELIDA | ||||||||||||||
LOBATOCEREBRIDAE | DIURODRILIDAE | ? | SIPUNCULA | DINOPHILIDAE | PROTODRILIDAE | PSAMMODRILIDAE | NEREIDIDAE | CAPITELLIDAE | SERPULIDAE | |||||
Lobatocerebrum riegeri n. sp. | Lobatocerebrum psammicola | Diurodrilus sp. | Jennaria pulchra | Phascolion strombus | Siphonosoma australe | Dinophilus gyrociliatus | Protodrilus sp. | Psammodrilus fauveli | Platynereis sp. | Capitella sp. | Pomatoceros lamarckii | Spirorbis cf. spirorbis | ||
Location of the ventral nerve cords | Intraepithelial | Intraepithelial | Intraepithelial | Intraepithelial | Intraepithelial | Intraepithelial | Intraepithelial | Intraepithelial | Intraepithelial | Intraepithelial | Intraepithelial | Intraepithelial | Intraepithelial | |
BRAIN | Lobular structure | + | + | ? | + | ? | ? | - | - | + | + | + | - | + |
Central neuropile | + | + | + | + | + | + | + | + | + | + | + | + | + | |
Number of brain commissures | 4 | ? | 4 | ? | 2 | 1 | 2 | 4 | 4 | 4 | 4 | 4 | 4 | |
Dorsal root (dorsal/ventral commissure) | + (+/+) | ? | + (+/+) | ? | ? | - (Not differentiated in this species) | ? | + (+/+) | + (+/+) | + (+/+) | + (+/+) | + (+/+) | + (+/+) | |
Ventral root (dorsal/ventral commissure) | + (+/+, individual fibres spread out) | ? | + (+/+) | ? | ? | - (Not differentiated in this species) | ? | + (+/+) | + (+/+) | + (+/+) | + (+/+) | + (+/+) | + (+/+) | |
NERVE CORDS OF THE CENTRAL NERVOUS SYSTEM | Number of posterior longitudinal nerve cords | 1 pair + 1 median cord | 1 pair (+1 median cord?) | 2 pairs | 1 pair | 1 pair | 1 pair (fused during development) | 3 pairs + median cord | 1 pair | 1 pair | 1 pair | 1 pair | 1 pair | 1 pair |
Median posterior nerve cord | + | ? | - | - | - | - | + | - | - | - | + | + | - | |
Number of rostral longitudinal nerve cords | 2 ventrolateral + < 7 additional, smaller ones | 2 (?) | >2 | ? | 0 | 0 | 0 | 0 (but innervation of tentacles) | 0 | 0 | 0 | 0 (but innervation of tentacles) | 0 (but innervation of tentacles) | |
GANGLIA AND COMMISSURES ALONG THE VENTRAL NERVE CORD | Total number of ganglia | 2 pairs | 2 pairs | 1 (fused pair) | ? | >2 | >2 (during development) | >2 | >2 | >2 | >2 | >2 | >2 | 1 (in larvae) |
Nonganglionated posterior commissures | >2 | 2 | >2 | 1 | ? | >2 (during development) | >2 | >2 | >2 | >2 | >2 | >2 | 1 (in larvae) | |
Presence of a subpharyngeal ganglion | + | + | + | ? | + | + (during development) | + | + | + | + | + | + | + | |
STOMATOGASTRIC NERVOUS SYSTEM | Stomatogastric nervous system | + (ring around the pharynx) | + (ring around the pharynx) | + (ring around the esophagus) | + (nerve cells in the pharyngeal epithelium) | + (ring around the esophagus | + (ring around the esophagus, during development) | + (ring around the pharynx) | + (ring around the esophaus) | + (ring around the esophagus, also tracing the esophagus) | + (ring around the esophagus) | + (ring around the esophagus) | + (fibre along the gut, ring around the esophagus) | - |
Origin of the stomatogastric nervous system | Postpharyngeal ganglion | Postpharyngeal ganglion | prebuccal ganglion | ? | brain (?) | brain (?) | Brain (dorso-posterior neuropile) | Brain | Buccal ganglion | Brain | Brain | Brain | - | |
PERIPHERAL NERVOUS SYSTEM | Grid of distinct longitudinal and circular nerves | ? | 1 pair of longitudinal nerves, several branches for innervating organs | Some nerves around the pharynx and gut, otherwise not present or not described | Nerve plexus | ? | Regular grid of longitudinal and circular nerves, nerve plexus dorsal to the ventral nervous system | ? | ? | Grid of distinct longitudinal and circular nerves | Grid of distinct longitudinal and circular nerves | Circular nerves in some segments | Grid of distinct longitudinal and circular nerves | |
References | This study | [61] | [58] | [91] | [92] | [92] | ||||||||