A new deepwater assfish, Bassozetus nielseni sp. nov. (Ophidiiformes: Ophidiidae), from the North Atlantic and West Indian oceans

  • Shinichi Tomiyama
  • Munehiro Takami
  • Atsushi Fukui
Full Paper


A new deepwater assfish, Bassozetus nielseni sp. nov., is described from 29 specimens [147–615 mm in standard length (SL)] collected from the North Atlantic and West Indian oceans. It is distinguished from 13 congeners by the following combination of characters: dorsal-fin rays 122–129, long rakers on first gill arch 11–14, oblique scales 20–25, abdominal vertebrae 13–14, head length 18.1–21.3 % SL, body depth at anal-fin origin 8.2–14.6 % SL, predorsal length 16.4–20.1 % SL, tail length 62.7–68.0 % SL, posterior tip of pelvic-fin rays anterior to anus, a single median basibranchial tooth patch, dorsal margin of sagittal otolith smooth, and fins pale yellowish brown (preserved condition).


Bassozetus compressus Bassozetus elongatus Neobythitinae New species Nielsen’s assfish Sexual dimorphism 



We are most grateful to the following for specimen loans: P.-L. Lin (ASIZP), J. Maclaine and T. Heath (BMNH), H. Endo and N. Nakayama (BSKU), P. Pruvost, R. Casse and Z. Gobsi (MNHN), G. Shinohara (NSMT), D. Catania (CAS), J.T. Williams and S.J. Raredon (USNM), J.G. Nielsen and T. Menne (ZMUC) and E.J. Hilton (VIMS). We also thank J.G. Nielsen, W. Schwarzhans (Hamburg, Germany) and two anonymous reviewers for helpful comments and G. S. Hardy (Ngunguru, New Zealand) for his critical reading of the manuscript. This study was supported in part by a Grant-in-Aid for Promotion of Scientific Research (C) (no. 25450280) from the Ministry of Education, Culture, Sports, Science and Technology, Japan, to the third author (AF).


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© The Ichthyological Society of Japan 2018

Authors and Affiliations

  1. 1.Marine Science MuseumTokai UniversityShizuokaJapan
  2. 2.School of Marine Science and TechnologyTokai UniversityShizuokaJapan

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