DNA barcoding reveals cryptic diversity of fish eggs in Equatorial Southwestern Atlantic

DNA barcoding presents a reliable and universal tool for species identification; however, few studies have used this methodology to analyze fish egg diversity in low-latitude seascapes. In the present study, DNA barcodes were used to assess the diversity of fish eggs in the Equatorial Southwestern Atlantic, a rich but understudied region. We sampled two seascapes for analyzing the fish diversity: seagrass and rhodolith beds. Collectively, 112 fish eggs were sorted for genetic analysis, of which 31 were successfully sequenced. One egg was successfully identified at the order level, three at the family level, 20 at the genus level, and seven at the species level. Several tropical fish species have not yet been barcoded and deposited in genetic databases; therefore, our novel research has expanded our knowledge of the diversity of fish eggs in low-latitude areas. Molecular identification revealed a cryptic diversity among the types of eggs collected from major tropical seascapes. Importantly, efforts should be made to improve the barcode database for fish eggs and larvae worldwide. This baseline information is essential for assessing the global environmental changes affecting fish diversity in coastal seas.