DNA Barcoding of Mullets (Family Mugilidae) from Pakistan Reveals Surprisingly High Number of Unknown Candidate Species

The mullets are a widespread group of ecologically and economically important fishes of disputed taxonomy due to their uniform external morphology. Barcoding and phylogenetic studies from various locations around the world largely highlighted the species diversity underestimation using morphological criteria used to establish the taxonomy of the family. Here, we investigated the mullet species diversity from Pakistan, a biogeographic area where nearly no mullet species were genetically characterized. Morphological examination of 40 mullets reveals 6 known species (Planiliza macrolepis, P. klunzingeri, P. subviridis, Crenimugil seheli, Ellochelon vaigiensis, and Mugil cephalus). Using a references DNA barcode library, the DNA barcode-based species identification flagged eight molecular operational taxonomic units (MOTUs) belonging to five genera (Crenimugil, Ellochelon, Mugil, Osteomugil, and Planiliza). Among these MOTUs, only one was already present in Barcode of Life Data system, all other representing new Barcode Index Numbers (BIN). These results emphasize the importance of the recognition of cryptic species and the necessity to re-evaluate the overall diversity by the genetic characterization of different species of this family. DNA barcoding is an effective tool to reveal cryptic species that need to be considered in conservation and management measures of fisheries in Pakistan