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Researchers from National Taiwan Ocean University, University of Taipei and the Smithsonian Institution have now described three new species of the conger eel genus Gnathophis, drawing on 130 specimens collected from the deep sea. The findings raise the number of Gnathophis species known from Taiwan from two to five.
Members of this genus are medium-sized eels of tropical and subtropical deep waters, recognisable by a blunt tail tip, a fleshy snout that projects beyond the teeth, and a small fleshy keel on the underside of the snout.
The team compared vertebral counts, the pores of the sensory lateral line, colouring and tooth patterns, and for two of the species they added DNA barcoding to confirm the distinction. The two barcoded species differ from each other by roughly 4.4 to 4.9 per cent in the gene examined, well beyond the variation seen within a single species.
Each name tells a small story about where the eel was found or how it looks:
- Gnathophis kbalanensis (Kbalan’s conger): named after “Kbalan”, an ancient name for the Yilan region of northeastern Taiwan, in use roughly 800 to 1,300 years ago. It is also known as Cabaran in Spanish and Kat-má-lán in Taiwanese. The largest specimen measured 472 millimetres, and the species is recognised by its blackish fins and a high vertebral count of 134 to 137.
- Gnathophis melanurum (black tail conger): named from the Greek melan, meaning black, and urum, meaning tail, in reference to its black tail fin. Its dorsal and anal fins are pale, which makes the dark tail stand out. It was found off both northeastern and southwestern Taiwan, mostly at depths of around 200 to 300 metres.
- Gnathophis nanhaiensis (Nan Hai’s conger): named after “Nan Hai”, the Chinese name for the South China Sea, where the holotype was collected at a depth of about 509 metres. The Latin ending -ensis means “originating in”. Known from only two specimens, it has pale fins and the highest vertebral count of the three, at 139 to 143.
The first two species share a feature that sets them apart from some of their relatives: the lateral line pores above the pectoral fin are raised, and the peritoneum, the lining of the body cavity, is black. Several of the specimens were ripe females carrying loose eggs, which suggests these waters may serve as spawning grounds.
The study also tidies up the regional record. An eel previously listed in Taiwan as Gnathophis xenica was confirmed to be a misidentification, and the researchers found no evidence to split the widespread G. heterognathos into separate species.
The work is dedicated to the late Dr David G. Smith, whose contribution to eel taxonomy inspired the first author.
Original source:
Huang J-F, Liao Y-C, Chan T-Y, Chen H-M, Smith DG (2026) The congrid eel genus Gnathophis in Taiwan (Anguilliformes, Congridae), with descriptions of three new species. ZooKeys 1287: 11-46. https://doi.org/10.3897/zookeys.1287.183842
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