Mitochondrial phylogeny, diversity, and ichthyogeography of gobies (Teleostei: Gobiidae) from the oldest and deepest Caspian sub-basin and tracing source and spread pattern of an introduced Rhinogobius species at the tricontinental crossroad

Here, we combined archived mitochondrial sequences for Ponto-Caspian gobiids with new sequences from the south Caspian basin to assess and evaluate its gobioid diversity and taxonomy, and to provide a first mitochondrial-based phylogenetic and phylogeographic framework. We demonstrate that: (i) Proterorhinus nasalis is the tubenose goby taxon in the saline waters of the southern Caspian Sea, whereas the name Pr. semipellucidus for the Azov/northern Caspian Sea/Volga River populations is likely be resurrected depending on the outcome of an integrative taxonomical approach; (ii) the deep-water goby Ponticola bathybius should be re-assigned to the genus Neogobius , as it is the sistergroup of N. melanostomus ; (iii) specimens previously identified as Po. cyrius and Po. iljini from the south Caspian basin appear conspecific with Po. iranicus and Po. gorlap , respectively, and should be omitted from the checklist of Iranian and south Caspian freshwater fishes; (iv) the low stand of the Caspian Sea during the Tyurkyanian regression is inferred to have led to the isolation and evolution of Po. iranicus ; and (v) similarities in genetic background, and invasion history of Rhinogobius sp. and Pseudorasbora parva in Iran and Turkmenistan indicate that the initial introduction of both species into the region possibly originated from Japan in the 1980s.