Morphology and DNA barcoding of some henicorhynchus and labiobarbus

Abstract

“Ca linh” are important economic fish species, which are abundant during the flood season in the Mekong Delta. In the region, there are currently four species belonging to two groups of short (Henicorhynchus siamensis and Henicorhynchus lobatus) and long dorsal fin bases (Labiobarbus siamensis and Labiobarbus leptocheila). Identification of species within each group based on morphology is extremely difficult. This research was aimed to combine morphology characteristics and DNA barcoding for accurate species identification of “ca linh” and understand their phylogeny relationships. Fish samples (H. siamensis (n=188), H. lobatus (n=135), L. siamensis (n=9), L. leptocheila (n=129)) were collected along the Mekong River. Initially, samples were morphologically classified and measured countable and morphometric traits. Then, COI (Cytochrome C Oxidase Subunit I) gene of each species was amplified. Principal component analysis based on morphometric data showed that four species were separated. Main morphometric characteristics that discriminated among 2 species groups included dorsal fin base, head length, head depth, pre-dorsal distance, pre-pectoral distance, distance between anal and caudal fin, caudal peduncle depth. Morphometric based discriminant analysis could classified correctly 100% individuals to their original species. The phylogenetic tree based on COI gene indicates two clusters of the two genera, short and long dorsal fin bases. They differ 15.5-16% COI sequences based on Kimura-2P genetic distance. Within each genus, two species of Labiobarbus were genetically differentiated while two species of Henicorhynchus were more similar. These results provide important information for identification of “ca linh” species and contribute to DNA barcoding databases of freshwater species.