Exploring the presence and characteristics of spiny eels (Mastacembelidae, Teleostei) in the Nile Delta: An analysis of morphology, molecular phylogeny, and taxonomy

This study presents the first record of a spiny eel species from the family Mastacembelidae in the Nile Delta region of Egypt, where this family was previously thought to be absent except in the Aswa River and Lake Victoria. Morphological and molecular methods were employed to confirm the identification of the newly identified species, based on seven collected specimens. Morphometric and meristic characters were used to compare the new species with other African and Asian Mastacembelidae and confirm its geographic distribution. In addition, molecular markers were used to further confirm the identification of mitochondrial genome [Cytochrome oxidase subunit I (COI), Cytochrome b (Cyt b), and D- loop], in integration with one nuclear marker [the first intron of the ribosomal nuclear marker S7 (RPS7)]. Results indicate that the newly reported species belongs to the genus Mastacembelus and is a close relative of Mastacembelus frenatus. This report of a new African species in the River Nile Delta expands our understanding of the geographical distribution range of the Mastacembelidae family.