Next-generation sequencing of historical type specimens of malabar blood snapper (Lutjanus malabaricus, Bloch and Schneider, 1801) and crimson snapper (Lutjanus erythropterus, Bloch 1790)

The fish family Lutjanidae is very species-rich and widely distributed in the Indo-West Pacific. Many species have not only high morphological similarities, but are also genetically difficult to distinguish. Ambiguous and contradictory nucleotide sequences in international nucleotide databases impede the DNA barcoding-based identification of snapper species, especially of the malabar blood snapper (Lutjanus malabaricus) and the crimson snapper (L. erythropterus). To reveal the DNA sequences of both species, the holotype of L. malabaricus (Bloch and Schneider, 1801) and the lectotype of L. erythropterus (Bloch, 1790) were analyzed by next-generation sequencing. The mitochondrial DNA sequences of both museum specimens were found to be 99.77% similar, suggesting that L. malabaricus and L. erythropterus belong to the same species and both terms should be used as synonyms. Many DNA sequences annotated as L. malabaricus and L. erythropterus in public nucleotide databases do not fall within the monophyletic clade of the type specimens. Additionally, this clade contains many unidentified specimens found on local markets in the USA and Australia. These findings give reason to carry out further taxonomic studies within the snapper family.