DNA barcoding and COI sequence variation in Mediterranean lanternfishes larvae

The potential use of Cytochrome cOxidase I (COI)-DNA barcode sequences for the molecular identification of lanternfish larvae from the Sicilian Channel was investigated at two levels: at an interspecific level by confirming species identificationbased on morphological characters; and at an intraspecific level to test for the presence of geographicalvariation of COI-DNA sequences. A reference library of COI sequences was constructed starting fromunambiguously identified specimens. Neighbor-joining analysis based on K2P genetic distances formednon-overlapping clusters for all species (Myctophumpunctatum, Ceratoscopelus maderensis, Hygophum benoiti, Electrona risso and Lobianchia dofleini) witha 100% bootstrap support for each. Additional COI sequences of lanternfishes from Atlantic Ocean andBalearic Sea samples deposited in BOLD system database were included in the dataset. The presentanalysis allowed the identification of unknown fish larvae and indicated that there is a relative congruencebetween morphological and molecular identification approaches. Our preliminary data in Myctophidaespecies confirm that COI gene can be used as an efficient species-specific marker that is also useful forassessing the geographical provenance of larvae. This information will likely be applicable to the investigationof the population structure in these poorly studied species.