Deep genetic differentiation between two morphologically similar species of wolf herrings (Teleostei, Clupeoidei, Chirocentridae)

Abstract

Wolf herrings (Chirocentridae; Clupeoidei) are commonly found in local fish markets throughout the Indo-West Pacific region where they constitute an auxiliary source of food and income for local communities. The validity of the two species of wolf herrings, Chirocentrus dorab Forsskål, 1775 and C. nudus Swainon, 1839, is only supported by slight morphological differences. The identification of either species is challenging, especially for juveniles, and precludes accurate assessments of these natural resources at a species level. As a step towards gaining better knowledge of the genetic structure of these fishes, we examined genetic differentiation between these two species by reconstructing their entire mitogenomic sequences using high-throughput sequencing technology. We found that the mitogenome of each species shared the same gene content and order that were the same for those found in most other teleost fishes. Despite their high morphological similarity, these two species of Chirocentrus were genetically well differentiated (p-distance = 16.3% at their cytochrome oxidase I). A mitogenomic time-calibrated phylogenetic analysis showed that wolf herrings originated about 35 million years ago, and they represent a case of morphological stasis. Furthermore, comparison of published and newly determined mitochondrial COI barcode region sequences from 22 individuals revealed species-level cryptic genetic diversity within C. dorab. Altogether, these mitochondrial data are effective in discriminating species within this genus and informing population genetic relationships within species of wolf herrings.