A new decapod crustacean faunule is described from the early Miocene of the Slovenian part of the Styrian Basin. The Ivnik Beds exposed at the Cinzat locality contain seven species: Calliax michelottii (Axiidea: Callianassidae), Lepidophthalmus paratethyensis sp. nov. (Axiidea: Callianassidae), Jaxea kuemeli (Gebiidea: Laomediidae), Styrioplax exiguus (Brachyura: Chasmocarcinidae), Goneplax gulderi (Brachyura: Goneplacidae), Neopilumnoplax pohorjensis sp. nov. (Brachyura: Mathildellidae) and Retropluma slovenica sp. nov. (Brachyura: Retroplumidae). Numerous specimens of well-preserved Styrioplax exiguus permitted its redescription and re-assignment of its familial placement to Chasmocarcinidae. Neopilumnoplax pohorjensis sp. nov. constitutes the first fossil occurrence of the genus known to date. The decapod association, as well as other faunal elements, suggests low-energy deep-water depositional environment with epibathyal water depth of more than 125 m. The studied locality is situated in the Ribnica-Selnica graben filled with sediments once deposited in the Central Paratethys sea. Based on the affinities of decapod genera of the Central Paratethys and the Proto-Mediterranean, we conclude that the exchange of decapod faunas between these regions was probably regulated by an anti-estuarine circulation permitting an easier incursion of species from the Proto-Mediterranean into the Paratethys and simultaneous hindering the Paratethyan endemics (Styrioplax) from entering the Mediterranean.Key words: Decapoda, early Miocene, Central Paratethys, Slovenia, deep-water environment, palaeobiogeography. DECAPOD crustaceans from Neogene strata of northeastern Slovenia are poorly known. Records are limited to isolated specimens from occasional construction or earth works, and no decapod association has been previously recorded.Previous records of Miocene decapods from the Slovenian part of the Styrian Basin (Table 1) are those by Glaessner (1928) and Mikuz (2003). Glaessner (1928) described Microplax exiguus on the basis of three specimens from the Langhian ('Badenian') mudstones of two different localities, the towns of St Egydi ( Sentilj) and St Leonhard (Lenart) within the Kungota Formation. Almost a century later, Mikuz (2003) reported on remains of Portunus monspeliensis Milne Edwards, 1860, from the grey sandstone of the same formation cropping out near the town of Sentilj.This study describes the first decapod crustacean faunule from Slovenia. The assemblage was collected from the Ivnik Beds at the locality Cinzat on the northern slopes of Mt Pohorje. Decapod remains are a dominant group in the grey to brownish siltstones of the early Miocene ('Karpatian') age.
GEOLOGICAL AND STRATIGRAPHICAL SETTINGThe studied locality Cinzat is situated in the RibnicaSelnica graben, within the westernmost parts of the Styrian Basin, Slovenia. It is situated approximately 15 km west of Maribor (GPS coordinates: 46°32 0 35.05″N, 15°26 0 35.15″E), a city near the northern Slovenian border