ИСТИНА

Great Meteor is a giant seamount rising from seabed at about 4500 m to a summit plateau of square 1450 km2 at average depth 287 m below sea level located at ~30ºN and at 1600 m from the nearest continental coast. The plateau is an isolated «sublittoral habitat» covered with biogenic coarse calcareous sand consisted largely of shells of planctonic foraminiferans and pteropod gastropods. Nematofauna is very diverse and represented by about 75 species belonging to 51 genera and 32 families. Dominant family is Selachinematidae, they follow by Comesomatidae, Desmodoridae, Ceramonematidae, Thoracostomopsidae and Neotonchidae. A peculiar feature of the assemblages is high percentage of predatory families Selachinematidae (mostly Latronema). Another peculiar feature is high percentage and diversity of Ceramonematidae. Most species are presented by new species belonging to genera common in shallow coarse sediments. A few typical deepsea genera such as Acantholaimus and Manganonema are also present but their percentage is low. Pattern of the species composition and morphological analysis support a hypothesis on intensive local speciation processes on the isolated seamount plateau. The study is supported by Russian Fund of Fundamental Researches, grant N 15-04-02597. 1Faculty of Biology, Lomonosov’s Moscow State University, 119991, Russia. E-mail: AVTchesunov@yandex.ru; 2Institute of Oceanology, Russian Academy of Sciences, Moscow, 117997, Russia