Records of cusk eels from Vietnam, with comments on the original description of Neobythites nanhaiensis (Actinopterygii, Ophidiiformes, Ophidiidae)

Two species of cusk eels, Neobythites nanhaiensis Chen, Zhao, Yang, Zhang, He, Zhang, Wang et Zhong, 2026 and Grammonus robustus Smith et Radcliffe, 1913 are reported based on specimens collected from Nha Trang, Vietnam. The specimens of N. nanhaiensis represent the northernmost record of this species and the specimen of G. robustus fills the distribution gap between the Philippines and eastern Australia. Detailed descriptions of both species and sagittal otoliths are provided and compared to data of other specimens. Moreover, we found that the original description of N. nanhaiensis was partly based on damaged specimens (tail regenerated), making the counts of dorsal-, anal-, and caudal-fin rays, and vertebrae, and some measurements unreliable, and the true variation of this species remains unknown.