Thelodonts have been found in the Bol'shaya, Matusevich, Obryvistaya, Pod"emnaya, Spokojnaya, Ushakov rivers and Cape October sections of October Revolution Island, and Komsomolets and Pioneer islands sections, Severnaya Zemlya Archipelago, Russia. Two new families, one new genus and six new species belonging to the orders Katoporida and Thelodontida are described from the Upper Silurian. Seven taxa are re-described. Scattered scales of Loganellia cuneata (Gross, 1947), Paralogania ex gr. martinssoni (Gross, 1967), Paralogania menneri n. sp., Valiukia flabellata n. gen., n. sp., Phlebolepis elegans Pander, 1856, Thelodus visvaldi n. sp., Thelodus matukhini n. sp., Thelodus ex gr. schmidti (Pander, 1856), Thelodus sp. indet. and Lanarkia? sp. are characteristic for the Ludlow part of the sequence (Ust-Spokojnaya Formation of October Revolution Island and its analogue on Pioneer and Komsomolets islands). Thelodus parvidens(?), Loganellia cuneata, Paralogania wilsoni n. sp., P. kachanovi n. sp., Paralogania sp. cf. P. borealis (Karatajute-Talimaa, 1978), Goniporus alatus (Gross, 1947) and Nikolivia elongata Karatajute-Talimaa, 1978 are distributed in the sections of Krasnaya Bukhta Formation on October Revolution Island and coeval strata of Pioneer Island (Pridoli). Thelodus visvaldi n. sp. is also present in Wenlock of Pioneer Island.
Thelodonti, Upper Silurian, Severnaya Zemlya Archipelago, scale morphology, histology