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Diel drift patterns of larvae of the endangered cyprinid Gnathopogon caerelescens in an inlet of the Ibanaiko Lagoon, connected to Lake Biwa in Japan, were assessed in April 2012. Peak occurrence of yolk-sac larvae was within a few hours after dark. Drift of newly hatched larvae is considered to be an important biological mechanism that ensures larval dispersal and recruitment from the inlets (spawning grounds) to the lagoon which functions as a nursery ground. [ABSTRACT FROM AUTHOR]

The cyprinid species of the genus Gnathopogon, exhibiting flexible morphological and ecological variation, include limnetic life forms. We examined the origin of the limnetic forms and the population divergence of the Japanese Gnathopogon species, using molecular phylogenetic and phylogeographic analyses. A Bayesian phylogenetic inference approach based on mtDNA cytochrome b sequence data revealed three major lineages in G. elongatus. One of them formed a monophyletic group with the limnetic species G. caerulescens, which is endemic to an ancient lake, Lake Biwa. The divergence of the G. caerulescens lineage was estimated to date back to the early Pleistocene. This precedes the formation of the extensive pelagic environment in the present Lake Biwa. However, the recent genetic divergence of G. caerulescens was inferred to originate in the present Lake Biwa in the late Pleistocene. Another lacustrine population in the Mikata Lakes was shown to belong to a different lineage from G. caerulescens. The majority of the population possessed unique, but non-monophyletic, haplotypes, suggesting a short evolutionary history. One of the cryptic lineages of G. elongatus discovered in the Ina Valley, the lower area of Lake Suwa, might be related to the extinct lacustrine subspecies G. elongatus suwae, which has been replaced by introduced congeners. The previous and ongoing introductions of Gnathopogon fishes would have produced genetic disturbance to the indigenous populations. [ABSTRACT FROM AUTHOR]

Freshwater fishes in the genus Paraleucogobio include two species, Paraleucogobio notacanthus and Paraleucogobio strigatus. In this study, we determined complete mitochondrial genomes of P. notacanthus and P. strigatus to clarify their phylogenetic positions. The two mitochondrial genomes showed similar gene arrangements, codon use, gene overlaps or gene intervals with the length of 16,596 bp and 16,598 bp. Our phylogeny revealed that P. notacanthus and P. strigatus were nested within Gnathopogon fishes. The findings indicate that Paraleucogobio is a junior synonym of Gnathopogon. [ABSTRACT FROM AUTHOR]

The complete mitochondrial genome ofGnathopogon argentatuswas determined to be 16,607 bp long circular molecule with a typical gene arrangement of vertebrate mitochondrial DNA. The complete mitochondrial genome ofG. argentatusis 16,607 bp in length with 56.02% AT content, including 13 protein-coding genes, 22 tRNA genes, 2 rRNA genes and 1 control region. The complete mitochondrial genome ofG. argentatuswas obtained for the first time and would play an important role in population structure and conservation genetic studies. [ABSTRACT FROM AUTHOR]