Genetic similarity between the South Atlantic and the western North Pacific Maurolicus (Stomiiformes : Actinopterygii) taxa, M-walvisensis Parin & Kobyliansky and M-japonicus Ishikawa: evidence for synonymy?

Abstract

An analysis of the 524 nucleotide long segment in the 16SrDNA mitochondrial gene of Maurolicus japonicus revealed that there are two major haplotypes (E and H) and two minor haplotypes (I and J), which comprise 63.6, 27.2, 4.6 and 4.6% of the population, respectively. The nucleotide sequence of the major haplotype E is identical to that of the most common haplotype in Maurolicus walvisensis (63.6% of the population). The other haplotypes of M. japonicus are almost identical to that of the haplotype E with only a single (haplotypes I and J) or three nucleotide differences (haplotype H). Phylogenetic trees of all the 16SrDNA haplotypes found thus far in the Maurolicus taxa show that the relationships among the haplotypes of M. japonicus and M. walvisensis are indistinguishable but that they are clearly distinctive from those of Maurolicus muelleri. Examination of the morphometric characteristics of specimens reveals similarities among the individuals of different haplotypes of M. japonicus and also between M. japonicus and M. walvisensis in almost all characteristics. The results suggest that despite the current ocean-wide allopatric distribution between M. japonicus and M. walvisensis, the two taxa are conspecific as M. japonicus. (C) 2008 The Authors Journal compilation (C) 2008 The Fisheries Society of the British Isles.