Integrating geometric morphometrics and DNA barcoding: A consolidated taxonomic tool in identifying selected cryptic Carangid species encountered in the Indian Ocean.

Abstract

Geometric morphometrics and mitochondrial cytochrome oxidase I (COI) DNA barcoding are crucial for identifying closely related cryptic carangid species. We integrated both taxonomic methods for promising identification within selected carangid groups, trevallies (Turrum coeruleopinnatum, Platycaranx malabaricus, and Atropus hedlandensis) and scads (Selar crumenophthalmus, Selar boops, and Atule mate). Despite a plethora of carangid barcode data, the knowledge bridge on carangid evolutionary footprints provides limited information on their origin, evolution, and distribution. Procrustes-defined data derived from shape differences between species and between morphs within species were analyzed by principal component analysis (PCA) and canonical variate analysis (CVA) (P < 0.0001), and were independent of intraspecific variation. Geometric morphometric clustering was evaluated using mtDNA COI barcoding, and each morph/species cluster was found to be compatible with the corresponding species. Average Kimura 2- Parameter (K2P) divergences were obtained in accordance with taxonomic hierarchy and were consistent with the 2% species delimitation: conspecific, congeneric, confamilial divergences were 0.28%, 4.50%, and 11.90% respectively and intraspecific and interspecific divergences were in the ranges (0.00-0.60)% and (2.10-18.70)% respectively. The greatest divergence was observed between the Indian and Indo-Australian Archipelago (IAA) individuals, whereas the lowest divergence was observed between the common ancestral cluster and IAA individuals. However, both consolidated taxonomic approaches provided a clear resolution of the selected carangid species over cryptic speciation. The origin of the carangid ancestor and its centered distribution in the IAA region are well described by regional characteristic divergences and are further explained by the center of origin and overlap hypotheses.