Labiobarbus genus (Roberts, 1993), belongs to the family Cyprinidae. This genus is freshwater fishes, mainly distributed in several parts of Asia. Due to their morphological similarities, it can be difficult to distinguish between different species, which may result in an inaccurate assessment of species diversity. This study aims to determine the number of species and quantity of genetic diversity of the Labiobarbus genus in the Mekong Delta.
Seventy-five samples for morphological species identification, in which 30 samples for DNA analysis were collected in the flooding areas along the Tien and Hau Rivers, including Long An, Dong Thap, An Giang, and Can Tho. Species identification was based on morphology and DNA barcoding methods using the mitochondrial DNA cytochrome c oxidase subunit I (COI) gene.
Morphological results showed that the two species are significantly different. The phylogenetic analysis indicates that the Labiobarbus genus is divided into two large groups. COI sequences of two species L. leptocheilus and L. siamensis have high levels (99-100%) of similarities compared to the same species reported in the GenBank database (Table 1). The average congeneric (inter-specific) Kimura-2P genetic distance between the two species (8.42%) is much larger than the intra-specific (conspecific) genetic distances of each species (0.31-0.38%). Conspecific genetic distances between populations of L. leptocheilus range from (0.26-0.41%), indicating high divergence within species. Besides, the genetic diversity of two Labiobarbus species with a slightly higher value in L. leptocheilus (Hd=0.8700 and pi=0.0031) compared to L. siamensis (Hd=0.7000 and pi=0.0038).
Keywords: DNA barcoding, genetic diversity, Labiobarbus genus, species identification