Chernyshev A.V.1,2, Magarlamov T.Yu.1 2013. Metameric structures in the subepidermal nervous system of the nemerteans with review of the metamerism in Nemertea // Invertebrate Zoology. Vol.10. No.2: 245–254 [in English].

1 A.V. Zhirmunsky Institute of Marine Biology FEB RAS, Vladivostok, 690059 Russia

2 Far Eastern Federal University, Vladivostok, 690600 Russia, e-mail: nemertea@fromru.com

KEY WORDS: Cephalothrix, metamerism, nemerteans, ring nerves, rhynchocoel septa, sudepidermal nervous system.

ABSTRACT: The subepidermal nervous system of five nemertean species (Tubulanus sp., Hubrechtella juliae, Cephalothrix simula, Quasitetrastemma stimpsoni, and Ototyphlonemertes martynovi) was studied using antibodies against serotonin (5-HT) and catecholamines (for H. juliae only) together with confocal laser scanning microscopy. Tubulanus sp. and H. juliae have closely situated transverse (semicircular) nerves connecting the dorsal nerve and/or the lateral nerve cords. Two kinds of metameric structures are found in the subepidermal nervous system of C. simula: closely situated transverse nerves and well-developed ring nerves spaced 380–750 μm apart. Closely situated transverse subepidermal nerves connect two subdorsal and two subventral longitudinal nerves in Q. stimpsoni and O. martynovi. Juvenile specimens of Q. stimpsoni (four days after hatching) lack both transverse and longitudinal subepidermal nerves. The examples of metamerism in nemertean morphology are discussed. The metameric ring nerves and rhynchocoel septa of cephalotrichid nemerteans are of chief interest, but further investigations of both structures are necessary for correct evolutionary interpretations.

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