Ilyophis singularis (Synaphobranchidae; Ilyophinae), a new deep-sea eel from the South China Sea

The new synaphobranchid eel Ilyophis singularis is described on the basis of two specimens (248–270 mm in total length) collected from the northeastern South China Sea at a depth between 1,612 and 1,665 m. The new species is characterized by a low number of vertebrae, with 116–118 total vertebrae, which is the smallest known for a species in Ilyophis . In addition, it differs from its congeners by the following combined characteristics: preanal vertebrae 36–37; sensory pores in supraorbital series 3 (pores absent above eye); sensory pores in infraorbital series 7 or 8 (2 or 3 pores behind eye); sensory pores absent on frontal and supratemporal regions; and body naked. The uncertainties for defining the two subgroups in Ilyophis are also discussed.