Complete mitochondrial genome of the snowy sheathbill ( Chionis albus , Charadriiformes: chionidae) and its phylogenetic implications

The snowy sheathbill (Chionis albus (Gmelin, 1789)) is a coastal Antarctic bird that breeds on Antarctic and sub-Antarctic islands. In this study, we report the first complete mitochondrial genome sequence of C. albus. The mitogenome is circular, 19,116 bp in length, and contains 13 protein-coding genes (PCGs), including an ND3 gene with an extra nucleotide, 22 transfer RNAs (tRNAs), and two ribosomal RNAs (rRNAs). Notably, a duplicated region of ∼2.3 kb includes ND6 and two tRNAs. The overall nucleotide composition is 30.29% A, 30.37% C, 14.56% G, and 24.78% T, with a GC content of 44.93%. Phylogenetic analysis based on all 13 PCGs placed C. albus firmly within Charadriiformes and clustered with C. minor and, more distantly, with Burhinus bistriatus. This newly characterized mitogenome provides valuable resources for future studies on the phylogeny, molecular evolution, and biogeography of Charadriiformes and the family Chionidae.