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Table 3 Compilation of features of the nervous system in representatives of different spiralian groups with previously proposed relationship to Lobatocerebrum riegeri n. sp

From: Detailed reconstruction of the nervous and muscular system of Lobatocerebridae with an evaluation of its annelid affinity

   ANNELIDA MOLLUSCA NEMERTEA GNATHOSTOMULIDA PLATYHELMINTHES XENACOELOMORPHA
   LOBATOCERBRIDAE SIPUNCULA ORBINIIDAE SOLENOGASTRES CAUDOFOVEATA GASTROPODA PALAEONEMERTEA ANOPLA BURSOVAGINOIDEA FILOSPERMOIDEA CATENULIDA NEMERTODERMATIDA
   Lobatocerebrum riegeri n. sp. Phascoliun strombus Scoloplos armiger Dorymenia sarsii Chaeoderma japonicum Helminthope psammibionta Cephalothrix linearis Procephalo-thrix linearis Lineus viridens Gnathostomula peregrina Rastrognathia macrostoma Pterognathia meixneri Stenostomum leucops Nemertoderma westbaldi
  Location of the ventral nerve cords Intraepithelial Intraepithelial/subepidermal Intraepithelial Subepidermal Subepidermal Subepidermal Subepidermal Subepidermal Subepidermal Intraepithelial Intraepithelial Intraepithelial ? (mainly subepidermal) Intraepithelia to subepidermal
BRAIN Lobular structure + ? + - + + + + + - ? (−) - - -
Central neuropile + + + + + + + + + + ? (+) + + - (only commissures formed)
Number of brain commissures 4 2 4 1 1 1 >2 >2 >2 1 ? (1) 1 1 2 rings (dorsally connected)
NERVE CORDS OF THE CENTRAL NERVOUS SYSTEM Number of posterior longitudinal nerve cords 1 pair + 1 median cord 1 pair 1 pair 2 pairs (+1 median cord) 2 pairs 2 pairs 1 pair 1 pair + 1 dorsal median + 1 ventral median cord 1 pair 1 pair 1 pair 1 pair 1 pair - (thin fibres, but no cords)
Median posterior nerve cord + - - + - - - + - + (just a short piece) ? (−) - - -
Number of rostral longitudinal nerve cords 2–9 0 0 - - 2 pairs ? 4 Approx. 8 pairs - ? >3 paired and 2 unpaired - -
GANGLIA AND COMMISSURES ALONG THE VENTRAL NERVE CORD Total number of ganglia 2 pairs >2 >2 >2 >2 >2 ? ? 1 pair 1 pair ? (1 pair) 1 pair ? ?
Nonganglionated posterior commissures >2 ? >2 >2 >2 >2 ? 1 ? 1 ? (1) 1 (2) ? -
Presence of a subpharyngeal ganglion + + + + + + + + + + ? (+) + + -
PERIPHERAL NERVOUS SYSTEM   Grid of distinct longitudinal and circular nerves Nerve plexus Grid of pairwise arranged longitudinal and several circular nerves per segment ? ? ? ? Intraepidermal plexus around the rhynchocoel Subepidermal plexus, commissural plexus, stomatogastric plexus, proboscidial plexus 5 longitudinal nerves 6 longitudinal nerves 3 dorsal longitudinal nerves ? ?
References   This study [57, 73, 74] [75, 76] [40, 41] [40] [43] [42, 48] [42] [77] [78] [17, 79] [17] [46, 80] [81, 82]
  1. Details of the brain, the ventral nervous system, the stomatogastric nervous system and the peripheral nervous system are given in an attempt to reveal common features or possible apomorphies in Lobatocerebridae. Presence of a character is labeled with +, absence with -, numbers and additional informations are given wherever possible. “?” indicates the lack of information in the references mentioned, while reinvestigations from this study (in the case of L. riegeri n. sp.) and assumptions based on additional references are included by putting the assessment in brackets (+) or (−). Only species with previously [812] or recently [7] suggested relationship to Lobatocerebridae were considered. Insufficient information in one species was supplemented with closely related species, based on the literature acknowledged in the reference-row