Morphological and Molecular Evidence of the Presence of the Ninespined Stickleback Pungitius pungitius (Linnaeus, 1758) Within Ukrainian Gasterosteids, Including New mtDNA Haplotypes—Which Issue for Fish Conservation in Ukraine?

Abstract

The Gasterosteidae, a family of marine, brackish and fresh water fish, is represented in Ukraine by the genera Pungitius and Gasterosteus. Among these, only the species Pungitius platygaster has hitherto been identified. However, our findings based on molecular cox1 DNA barcoding of collected material have confirmed the additional presence of Pungitius pungitius in the Dnipro River in Ukraine. This species has long remained hidden from scientific scrutiny, due to its diminutive size, lack of commercial significance and morphological similarities with a sister species. Our molecular DNA barcoding analysis has allowed the conclusive identification of this elusive species and provided an insight into its distribution and ecological relevance within inland waters in Ukraine. To examine and compare the haplotype diversity, we analysed our data of P. platygaster, P. pungitius and Gasterosteus aculeatus with those available in public repositories. Our findings demonstrate the presence of novel haplotypes in the region for all species. This support the theory P. pungitius is not a recent invasion in the region. Our findings demonstrate valuable role of advanced molecular methodologies in unravelling the biodiversity of aquatic ecosystems, particularly in the case of overlooked and often marginalized taxa. We also explore the current worldwide and regional conservation status of the species, contributing to the future studies and the population management.