On the Taxonomic Status of the Red Icefish Channichthys rugosus (Notothenioidei: Channichthyidae) from the Kerguelen Islands (South Ocean)

Abstract

The presented work is the final part of the taxonomic revision of the Antarctic icefishes of the genus Channichthys Richardson, 1844 (Notothenioidei: Channichthyidae) from the Kerguelen Islands, the species composition of which was discussed until recently. Based on the morphological study of all available specimens from the ZIN and BMNH collections (including the holotype), a comprehensive redescription of the Red icefish Channichthys rugosus Regan, 1913 from the waters of the Kerguelen islands (South Ocean) was carried out, including external morphology, seismosensory system, gill apparatus, and axial skeleton. As a result, new diagnostic features of Red icefish were discovered and previously known ones were clarified, which made it possible to confirm the species validity. Comparison with other valid species icefishes was done. Channichthys rugosus differs from Ch. rhinoceratus Richardson, 1844 by a high anterior dorsal fin, the fin membrane of which reaches the apexes of its longest rays (does not reach in Ch. rhinoceratus), as well as a narrow and concave interorbital space (compared to the wider and flat one), by stronger granulation and a uniform reddish body color (dark spotted-marble in Ch. rhinoceratus). Channichthys rugosus differs from Ch. velifer Meissner, 1972 by the number of rays in the first dorsal fin (7–9 versus 9–12) and pectoral fin (18–20 versus 20–21), the presence of bone plaques in the proximal part of the medial lateral line (absent in Ch. velifer), and monochromatic reddish body coloration (spotted in Ch. velifer). Channichthys rugosus differs from Ch. panticapaei Shandikov, 1995 by the presence of only 1 row of gill rakers on the first gill arch (2 rows in Ch. panticapaei) and by light coloration (brownish-black in Ch. panticapaei).