We wish to thank Mikael Thollesson (Evolutionary Biology Centre, Uppsala University), who, in the 1990s, noted the presence of Swedish specimens of the then Dendronotus robustus in the collections at GNM. We thank Anna Persson (Swedish Museum of Natural History) and Torsten Hugo Struck (Oslo Natural History Museum) for providing collection information. We would particularly like to thank O.L. Zimina for providing specimens of D. robustus and D. velifer collected in the Arctic seas. A.G. Bogdanov and G.N. Davidovich (Electron Microscopy Laboratory MSU) are thanked for support with electron microscopy. Richard Willan (Museum and Art Gallery of the Northern Territory, Australia) and two anonymous reviewers are thanked for their constructive comments on the manuscript. This study was supported by a research grant from MSU Zoological Museum (АААА-А16-116021660077-3, for deposition of specimens) and The Russian Science Foundation (grant 14-50-00029, for the collection of specimens and molecular and morphological analyses).
Received: 11 August 2017
Revised and accepted: 21 November 2017
Published online: 22 December 2017
Editor: B.W. Hoeksema