Complete mitochondrial genome of Ladislavia taczanowskii (Cypriniformes: Gobionidae)

Abstract Mitochondrial genomes of two individuals of Tachanovsky’s gudgeon Ladislavia taczanowskii have been determined on the basis of Sanger dideoxy sequencing. The gene compositions of two genomes contain 13 protein-coding genes, 2 rRNA genes, 22 tRNA genes, and 1 control region with the same length 16,614 bp. The phylogenetic tree reveals that the monotypic genus Ladislavia is a sister group of the subfamily Gobioninae within the family Gobionidae.

The monotypic genus Ladislavia is represented by the single species Tachanovsky's gudgeon, Ladislavia taczanowskii Dybowski 1869 that it is placed into the family Gobionidae within the order Cypriniformes (Tan and Armbruster 2018). Ladislavia taczanowskii is a small stream fish, distributed in the China, Korea, Mongolia, and Russia (Fricke et al. 2021). Two new mitochondrial genomes of Ladislavia taczanowskii were obtained in the present study. These data could be used to clarifythe systematic position of this species within the Gobionidae.
The gene compositions of two new mitochondrial genomes (GenBank Accession No. MT897994 and MT897995) are the same to contain 13 protein-coding genes, 2 rRNA genes, 22 tRNA genes, and 1 control region with the same length 16,614 bp and similar A þ T base composition of 55.27% or 55.28%. The two mitochondrial genomes also display the same patterns in codon use and gene arrangements. There are two kinds of start codons (ATG and GTG) and four types of stop codons (TAA, TA-, TAG, and T-) in the 13 protein-coding genes. The order of gene arrangements is the same as other published mitochondrial genomes of the family Gobionidae (e.g. Tong and Fu 2019;Yi and Fu 2020;Chai and Fu 2020). There are a total of 52 bp nucleotide difference between the two mitochondrial genomes. The phylogenetic tree (Figure 1) reveals that the monotypic genus Ladislavia is a monophyletic group, and it is a sister group of the subfam-ily Gobioninae within the family Gobionidae with relatively high Bootstrap confidence (85%).

Disclosure statement
No potential conflict of interest was reported by the authors.

Funding
This study was funded by National Natural Science Foundation of China [grant number 31872209].

Data availability statement
Two new mitochondrial genomes with accession numbers MT897994 and MT897995 could be available in the GenBank: https://www.ncbi.nlm. nih.gov/nuccore/ MT897994 or MT897995.