Characterization of the complete mitochondrial genome of Discogobio longibarbatus (Cypriniformes, Cyprinidae), an endangered and endemic species from China

Phylogenetic analysis based on the complete mitochondrial genome of Discogobio brachyphysallidos (Cypriniformes: Cyprinidae) suggests the need for taxonomic revision at the genus level

Discogobio brachyphysallidos Huang 1989 is a Cyprinidae fish species that is endemic to the upper Pearl River. In the present study, the complete mitochondrial genome of D. brachyphysallidos collected from the Nanpanjiang River was sequenced and annotated. The mitochondrial genome encompassed 13 protein-coding genes, two ribosomal RNA (rRNA) genes, 22 transfer RNA (tRNA) genes, and the control region (D-loop). The total length of the mitochondrial genome was determined to be 16,594 base pairs (bp), with a GC content of 41.7%. Phylogenetic analyses revealed that D. brachyphysallidos may be a sister to D. longibarbatus and D. macrophysallidos. These findings provide insight into the genetic information and phylogenetic relationships of D. brachyphysallidos.

Complete mitochondrial genome of Guigarracailaoensis Wang, Chen & Zheng, 2022 (Cypriniformes, Cyprinidae) and its phylogenetic implications

Guigarracailaoensis is a member of family Cyprinidae, subfamily Labeoninae (Cypriniformes) which was recently discovered in southwestern China. Following its initial description, additional information on this species has remained notably scarce. In the current study, we assemble the complete mitochondrial genome (mitogenome) of G.cailaoensis using the Illumina sequencing platform. The mitogenome is identified as a circular, double-stranded DNA sequence of 16,593 base pairs, encompassing 13 protein-coding genes (PCGs), 22 transfer RNA genes, two ribosomal RNA genes, and a putative control region. Maximum-likelihood and Bayesian-inference approaches were used to construct phylogenetic trees for three datasets: (i) PCG sequences of the complete mitogenome (dataset 1); (ii) PCG sequences of the complete mitogenome combined with nuclear DNA (ncDNA) (Rag1) sequence (dataset 2); and (iii) ncDNA (Rag1) sequences (dataset 3). Phylogenetic analyses position G.cailaoensis as a sister taxon to the lineage consisting of Paraqianlabeolineatus Zhao, Sullivan, Zhang & Peng, 2014 and Pseudogyrinocheilusprochilus Fang, 1933 in dataset 1, and to Pseudogyrinocheilusprochilus in dataset 2, species lacking an oral disc on the lower lip. However, G.cailaoensis showed a close relationship to the lineage consisting of Discogobio and Discocheilus in dataset 3, species possessing an oral disc on the lower lip. Nonetheless, a variety of species with an oral disc on the lower lip are clustered into different lineages across the three datasets that may indicate that the development of the oral disc is homoplastic within the subfamily Labeoninae. The outcomes of this study have the potential to support conservation efforts for this species and to enrich our understanding of genetic resources in the area.

Complete mitochondrial genome of Yunnan-Guizhou Plateau endemic fish, Discogobio macrophysallidos, in China

The complete mitochondrial genome of Discogobio macrophysallidos was first determined and analyzed in this work. Its mitochondrial genome is 16,593 bp in length, consisting of 13 protein-coding genes, 22 transfer RNA (tRNA) genes, two ribosomal RNA (rRNA) genes, and a non-coding control region, and its gene order was consistent with other fishes. Phylogenetic analysis showed that D. macrophysallidos were clustered with other three species of Discogobio. The complete mitogenome of D. macrophysallidos provides new molecular data for the further phylogenetic study of the genus of Discogobio.

Mitogenomic characterization and systematic placement of the Congo blind barb Caecobarbus geertsii (Cypriniformes: Cyprinidae)

This study presents the first complete mitochondrial genome (mitogenome) of Caecobarbus geertsii, the Congo blind barb, a cave-dwelling, CITES-protected, cyprinid fish endemic to the Lower Congo basin (DRC). The length of the circular mitogenome is 16,565 base pairs. The 13 protein coding genes, 2 ribosomal RNA genes and 22 transfer RNA genes are similar in position and direction to those of other members of the family Cyprinidae. Phylogenetic analyses including 28 complete mitogenomes from representatives of the subfamily Smiliogastrinae (Cyprinidae), showed that Caecobarbus was nested within a clade including representatives of the genus Enteromius. The data presented in this study provide information on the molecular identification and classification of this threatened species. The results further suggest the need for a taxonomic revision of the genus Enteromius.