LAUSR

Abstract Recent phylogeographic study pointed to the existence of highly divergent and endemic populations of the crayfish genus Austropotamobius in the Apuseni Mountains, Romania. These populations may have split ∼15 Ma from the Dinarides and evolved in isolation due to the tectonic north-eastern movement of the Tisza-Dacia mega-unit (including the Apuseni Mountains) through the Pannonian Basin during the Miocene. Molecular and morphological evidence supports that these populations are a new species of crayfish, Austropotamobius bihariensis n. sp, named for the region of Biharia. The bPTP approach supported a new species clade by 0.89 Bayesian Support Value, diverging from the sister clade of Austropotamobius torrentium (haplogroup ZV) by 43 mutational steps in 582 base length nucleotides of COI mtDNA sequences. The differentiating morphological features are the lack of denticulation on the lower edge of the antennal scale, a significantly shorter bell-shaped rostrum, and fewer tubercles on the chelae palms than its relative. Its distribution is geographically restricted to upper sectors of the Criș rivers basins, western Apuseni Mountains, Romania and it prefers cleaner waters than A. torrentium. Conservation measures are highly recommended.