Korean sand burrower (Limnichthys koreanus), a new creediid fish from tidal waters of Jeju Island

NEWS - Korean sand burrower (Limnichthys koreanus) was described based on the holotype and 11 paratypes from the subtidal waters of Seogwipo, Jeju Island, Korea, which was previously considered to be the anti-equatorial L. fasciatus in the Northern Hemisphere. Molecular analysis of mitochondrial COI and 16S genes found genetic divergence of 9.4% and 15.0% between the new species and the topotype specimen of L. fasciatus.

Creediidae consists of 8 genera with 18 species that are distributed globally and are mostly concentrated in subtropical and tropical coastal waters of the Indo-Pacific Ocean. These fish are known as sand burrowers, small, slender sand-dwelling fish that camouflage and hide in the uppermost layer of sand while waiting for prey.

Six species of Limnichthys are currently recognized as valid: L. fasciatus Waite (1904), L. marisrubri Fricke & Golani (2012), L. nitidus Smith (1958), L. orientalis Yoshino, Kon & Odabe (1999), L. polyactis Nelson (1978) and L. rendahli Parrott (1958). They show anti-equatorial distributions, except for L. nitidus which occurs in tropical to temperate waters of the Indo-Pacific Ocean.

Morphological and molecular comparisons of specimens from Korea in the Northern Hemisphere show that they differ from the topotype examples of L. fasciatus from southeastern Australia. Specimens of the new species were collected during a monitoring survey of subtropical fish species from the subtidal zone of Jeju Island, Korea.

L. koreanus differs from all other Limnichthys species by the following combination of coloration and morphological characteristics: 38-40 vertebrae, 0-6 dorsal saddles connecting the mid-lateral lines, small infraorbital sensory pores, one median interorbital pore, and well-developed vomerine teeth.

The researchers analyzed 12 specimens from 1-2 meters depth that were initially thought to be L. fasciatus. The new species has spots on the dorsal fin. The number of dorsal saddle patterns ranges from 5 to 9. Limnichthys species typically have 8 caudal fin segments, however, L. koreanus has 8-9 branched caudal fins.

The new species is only known from Jeju Island, Korea. They inhabit relatively thick sand (or possibly fine gravel) substrates, often hiding almost entirely in the sand in the subtidal zone. They dart out to catch prey and then return to their original position. Females have mature eggs in their gonads from June to August, 522 eggs per individual and 0.62-0.65 mm in diameter.

Original research

Lee Y-J, Kim J-K (2024). Limnichthys koreanus, a new species of creediid fish (Teleostei, Acropomatiformes, Creediidae) from Korea. ZooKeys 1214: 59-75, DOI:10.3897/zookeys.1214.128977

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