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. 2023 Mar 7;8(3):352-358.
doi: 10.1080/23802359.2023.2167479. eCollection 2023.

Characterization of the complete mitochondrial genomes of two Critically Endangered wedgefishes: Rhynchobatus djiddensis and Rhynchobatus australiae

M J Groeneveld  1 , J D Klein  1 , R H Bennett  2 , A E Bester-van der Merwe  1
Affiliations

Characterization of the complete mitochondrial genomes of two Critically Endangered wedgefishes: Rhynchobatus djiddensis and Rhynchobatus australiae

M J Groeneveld et al. Mitochondrial DNA B Resour. .

Abstract

We present the complete mitochondrial genomes of the Critically Endangered whitespotted wedgefish, Rhynchobatus djiddensis (Forsskål, 1775), and bottlenose wedgefish, Rhynchobatus australiae (Whitley, 1939), with the R. djiddensis mitogenome documented for the first time. The genomes for R. djiddensis and R. australiae are 16,799 and 16,805 bp in length, respectively. Both comprise 13 protein-coding regions, 22 tRNA genes, two rRNA genes, and a non-coding control region. All protein-coding regions consistently start with the ATG start codon; however, the alternative start codon GTG is observed at the start of the COX1 gene. NADH2, COX2, and NADH4 have incomplete stop codons: T or TA, and tRNALeu and tRNASer , have atypical codons: UAA, UGA, GCU, and UAG. The phylogenetic analysis places R. djiddensis and R. australiae within the Rhynchobatus genus, separate from other families in the order Rhinopristiformes. We also highlight the most variable gene regions to expedite future primer design, of which NADH2 was the most variable (4.5%) when taking gene length into account. These molecular resources could promote the taxonomic resolution of the whitespotted wedgefish species complex and aid in the genetic characterization of populations of these and related species.

Keywords: Ion Torrent; Rhinopristiformes; mitogenomes; phylogenetic analysis; rhino rays.

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Conflict of interest statement

There are no financial conflicts of interest to disclose.

Figures

Figure 1.
Figure 1.
Species reference images of (A) Rhynchobatus djiddensis (Photo by the South African Institute for Aquatic Biodiversity), the whitespotted wedgefish, with prominent black markings between eyes, large number of white spots and black pectoral marking surrounded by four or more white spots and (B) Rhynchobatus australiae (Photo by John Nevill), the bottlenose wedgefish, with bottle-shaped snout slightly constricted near tip, three white spots aligned over the pectoral marking (usually two spots below), a short line of well-demarcated white spots on the mid dorsal surface and no spots on the tail (TL = 137 cm).
Figure 2.
Figure 2.
Gene maps of the Rhynchobatus djiddensis (ON065568) and Rhynchobatus australiae (ON065567) mitogenomes. The outermost circle genes are transcribed clockwise and the rest counter clockwise.
Figure 3.
Figure 3.
Maximum-likelihood phylogeny of five families from the order Rhinopristiformes based on the concatenated dataset of 13 protein-coding genes, with members of the families Rajidae and Arhynchobatidae included as outgroups. Numbers at nodes indicate bootstrap values. GenBank accession numbers are given adjacent to the species name, scale bar indicates groupings of species into families and the taxa in bold are the mitogenomes from this study.
See this image and copyright information in PMC

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