The taxonomic status of Japanese threadfin bream Nemipterus japonicus (Bloch, 1791) (Perciformes: Nemipteridae) with a redescription of this species from the south china sea based on morphology and DNA barcodes

Abstract

Because of its importance as a food source, Nemipterus japonicus (Bloch, 1791) (Nemipteridae) or Japanese threadfin bream is the best studied of these taxa, and numerous investigations have examined its fisheries, its biology and biochemistry. Despite such intensive work, the taxonomic status of N. japonicus has never been seriously questioned and it is regarded as a common species, widely distributed throughout the Indo-Western Pacific Ocean. In fact, Bloch's description of the type specimen of N. japonicus has ambiguous collection data and lacks a designation for the type locality, though it is probably Java. In this paper, DNA barcode results based on COI gene support the existence of two geographically separated lineages of the Japanese threadfin bream, both being an Indian Ocean and western Pacific lineage, with 2.7% sequence divergence, and the results indicate a possible existing of some cryptic species. The two lineages also possess a diagnostic difference in their belly color, with specimens in the South China Sea having a silver belly, while those from the Indian Ocean isolate specimen have a yellow coloration. Based upon new collections from the South China Sea, this species from the western Pacific is morphologically redescribed and its details of DNA barcode diversity are shown for the future investigations.

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“…Environmental heterogeneity and life-history traits could be factors elevating the variability. A similar divergence value of 2.7% had been previously reported (Ning et al 2015) in N. japonicus populations from the Indian Ocean and West Pacific Ocean which was attributed to presence of cryptic species. Lim et al (2014) reported that while the populations of N. japonicus in the Straits of Malacca were panmictic from the Perlis waters in the Northwest to Kuala Sedili in the Southeast, a distinct cluster clade was observed in the South China Sea population of Tok Bali.…”

“…The parallel findings with Ning et al (2015) and Lim et al (2014) signifies the presence of a genetic barrier between the Indian Ocean and South China Sea for this demersal fish with the Straits of Malacca being the focal point of the two groups. Although on a smaller sizes, a detailed inspection showed that the same trend was also observed in N.…”

Molecular systematics of threadfin breams and relatives (Teleostei, Nemipteridae)

“…The Sunda Shelf barrier seems to contribute to this deep genetic break (Table 2). However, differences in colour pattern between West Pacific and Indian Ocean forms described by Ning et al (2015) are not always clear-cut as we found no difference among our samples; morphological distinction requires further work.…”

“…For the most studied species, N. japonicus , Ning et al . (), using morphological and molecular methods, found two distinct cryptic species within this previous recognized single species, distributed in the Indian Ocean and West Pacific, respectively. Lim et al .…”

“…For the most studied species, N. japonicus, Ning et al (2015), using morphological and molecular methods, found two distinct cryptic species within this previous recognized single species, distributed in the Indian Ocean and West Pacific, respectively. Lim et al (2014) analysed samples from both coasts of Malaysian Peninsular based on sequences from mitochondrial gene cytochrome b and found that this species might contain a regional cryptic species or distinct population in Kuala Besar in eastern Peninsular Malaysia.…”