Abstract
A new palaeobotanical site was recovered at artificial excavations within the city district of Ústí nad Labem called Mojžíř in northern Bohemia (Czech Republic) that yielded slabs of Oligocene tephritic pyroclastic rocks with plant impressions. The fossiliferous layer belongs to the Děčín Formation of the České středohoří Mts. dated to the Oligocene (30.8-24.7Ma).
One of the recovered fossils belongs to a new leptosporangiate fern matching modern representatives of Polystichum Roth (Dryopteridaceae Herter). These frond fragments are partly fertile and allow studying the position of sori and details of indusia and spores.
This fossil fern is described here as a new species of Polystichum, P. pacltovae Kvaček sp. nov., which matches the modern European species of Polystichum, namely Polystichum braunii (Spenner) Fée. Accompanying plant fossils include another fern frond described as "Aspidium" elongatum Heer (non Swartz) of unknown affinities, fragmentary needles assigned to Pinus cf. hepios (Unger) Unger of the Pinaceae and leaf impressions of Betulaceae comparable to Betula brongniartii Ettingshausen.