Population study of the freshwater halfbeak Hemirhamphodon pogonognathus (Bleeker, 1866) in Peninsular Malaysia: Preliminary evidence of new taxon
Lim,H.C1. and Siti Azizah,M.N. 1,2
1School of Biological Sciences Universiti Sains Malaysia Penang 11800, Malaysia; 2Centre for Marine and Coastal Studies Universiti Sains Malaysia. Corresponding Author: [email protected]
The Hemirhamphodon pogonognathus is a livebearer freshwater halfbeak and it is the most widespread species in this genus. Its habitat covers almost all of the Sundaland river basin except northern Borneo (Sabah) and even extends out of Sundaland to the Moluccas (Halmahera). The existing literature documents H. pogonognathus as the only species to be found in Peninsular Malaysia. Thus, a population study of H. pogonognathus of Peninsular Malaysia was conducted to assess the genetic variability and attempt to discover new Hemirhamphodon species in Peninsular Malaysia (if existing) that might have been misidentified and assigned to H. pogonognathus. The preliminary result reported the occurrence of an unknown taxon morphologically similar to H. pogonognathus in Peninsular Malaysia. This was based on ten representative populations across several states in Peninsular Malaysia utilizing a 830 bp sequence composed of a 684 bp partial mitochondrial DNA cytochrome b (cyt b) gene and 146 bp of tRNA-Glu. Values of genetic divergence (Kimura 2 parameter) among eight of the ten populations ranged from 0.4% to 1.5% while these eight populations were 12.9% to 14.3% diverged from the Jeram Pasu (east Peninsular) and Lata Belatan (east Peninsular) populations (1.2% of genetic divergence between these two populations). The constructed Neighbour Joining (NJ) and Maximum Likelihood (ML) phylogenetic trees using Kimura 2 parameter and Hasegawa-Kishino-Yano (HKY+G) model respectively isolated the Jeram Pasu and Lata Belatan populations into a discrete cluster. Thus, this study provided preliminary evidence of the presence of sibling species of the H. pogonognathus in Peninsular Malaysia. More detailed investigation is required to support this finding.
Keywords: Hemirhamphodon pogonognathus, cytochrome b