From the Oligocene onward, there was a large network of inland seas, parallel to the developing Mediterranean Sea and via changing ways, intermittently connected with the Mediterranean and the Indo-Pacific. This vast northern domain, covering a large part of the European continent, was
called Paratethys and was further diﬀerentiated into the Western, Central and Eastern part. Sediments of the Central Paratethys sea are now exposed in Hungary. The most widespread are the strata of the Badenian age. The Central Paratethyan regional stage Badenian (approximately 15.2–12.6 million years ago) is equivalent to the Mediterranean and global middle Miocene stages Langhian and early Serravallian. During that time, shallow marine environments hosted a diversity of organisms, including decapod crustaceans, which remains are not infrequently found at exposed localities with Badenian strata. Until now, nearly a hundred decapod species have been identified from the Badenian of Hungary. All of them are treated in detail here, providing detailed descriptions, remarks on occurrences and also graphical representation of each of them, including the type material. Together with the systematic overview of 99 decapod species, a synopsis of all Hungarian localities yielding Badenian decapods is provided. The systematic section, forming a major part of the book, is introduced with an identification key to all discussed taxa. Taxonomic treatment of respective species resulted in the recognition of ten new combinations, including Gilvossius roztoczensis (Müller, 1996) comb. nov., Eucalliaxiopsis pseudorakosensis (Lőrenthey in Lőrenthey, Beurlen, 1929) comb. nov., Anisopagurus leganyii (Müller, 1984a) comb. nov., Anisopagurus corallinus (Müller, 1996) comb. nov., Tetralobistes cserhatensis (Müller, 1984a) comb. nov., Pugetia oroszyi (Bachmayer, 1953a) comb. nov., Parthenopoides tetenyensis (Müller, 1984a) comb. nov., Derilambrus szaboi (Müller, 1974b) comb. nov., Achelous monspeliensis (A. Milne-Edwards, 1860) comb. nov., and Venitus aquensis (A. Milne-Edwards, Brocchi, 1879) comb. nov. Additionally, several species are considered synonymous with species described earlier. Pagurus retznensis Collins, 2014 is considered a junior subjective synonym of Petrolisthes haydni Müller, 1984a. Glabropilumnus nitidus Collins, 2014 and Portunus muelleri Collins, 2014 are both considered junior subjective synonyms of Rakosia carupoides Müller, 1984a.