Zoogeography and Systematics of Six Deep-Living Genera of Synaphobranchid Eels, with a Key to Taxa and Description of Two New Species of Ilyophis

An extensive series of deep-sea synaphobranchid eels was studied, primarily from previously unreported Russian collections in the southern Indian and southwestern Pacific oceans, Together with previous records, new Russian records provide a worldwide summary of the geographic and bathymetric distributions of the 14 species comprising the genera Diastobranchus, Haptenchelys, Histiobranchus, llyophis, Simenchelys, and Synaphobranchus. A diagnostic key defines species in these genera, including two newly discovered species of Ilyophis. The multi-character key facilitates unequivocal identification of synaphobranchid specimens. Diastobranchus and Histiobranchus are re-established as genera distinct from Synaphobranchus. Diagnoses of subfamilies and genera are refined, The zoogeography of studied taxa is summarized.