A new bivalve community from the lower Ludlow of the Prague Basin (Perunica, Bohemia)

The new shallow-water Bivalvia Janicula potens Community from the lower Gorstian carbonate platform influenced by the Svaty Jan Volcano activity in the Prague Basin, Bohemia is composed of 32 species [Slava sathon Kriz, 1985 (Slavidae); Cardiola donigala Kriz in Kriz & Serpagli, 1993, Cardiola signata Barrande, 1881, Cardiola aff. geminans Barrande, 1881 (Cardiolidae); Dualina amina sp. nov. (Antipleuridae); Mila parvula Kriz in Kriz & Serpagli, 1993 (Stolidotidae); Algerina aff. algena Kriz, 2008, Tetinka costulifera sp. nov. (Spanilidae); Macrodesma enigma sp. nov. (Cyrtodontidae); Phthonia regularis (Barrande, 1881) (Mytilidae); Ambonychia volitans (Barrande, 1881), Amphicoelia pojetana sp. nov., Mytilarca parens (Barrande, 1881), Mytilarca sp. (Ambonychiidae); Molinicola bohemica sp. nov. (Pterineidae); Palaeopecten radvani sp. nov., Palaeopecten sp. (Leiopectinidae); Rhombopteria perunicola sp. nov. (Rhombopteriidae); Praeostrea bohemica Barrande, 1881 (Praeostreidae); Butovicella migrans (Barrande, 1881) (Butovicellidae); Mimerodonta phaseolus sp. nov., Janicula potens (Barrande, 1881), Goniophora tyri Liljedahl, 1984, Goniophora ascia sp. nov., Goniophora compta sp. nov., Goniophora solci sp. nov., Goniophora sp. (Modiomorphidae); Goniophorina nitidula sp. nov. (Goniophorinidae); Cymatonota prolata sp. nov., Cimitaria liscina sp. nov., Cimitaria cf. liscina sp. nov., Sanguinolites? drupa sp. nov. (Grammysiidae)]. In the paper one new genus (Janicula gen. nov.), and 15 new species are described. The Janicula potens Community occupied the environment of protected well-ventilated shallow-water flats, locally overgrown by algae, with carbonate sedimentation influenced by direct ash falls and the subsequent sedimentation of volcaniclastics by currents around the volcanic archipelago. It is accompanied by a rich benthos, especially crinoids, corals, gastropods, and brachiopods together with abundant trilobites, rostroconchids, common cephalopods, stromatoporids, relatively rare ostracods, tergomyans, polyplacophorids, worms, bryozoans, sponges, and algae. It is classified as a part of the Coral-Crinoid Community Group which in the Prague Basin, Bohemia includes the homologous and analogous late Homerian, Wenlock Coral-Leptaenid Community, Hircinisca-Ancillotoechia Community, and Septatrypa lissodermis-Cyrtia maior Community, the early Gorstian, Ludlow Atrypa fumosa Community, and the Coniproetus-Protocymostrophia Community. The Janicula potens Community from the Lisci Quarry locality near the Amerika gamekeeper's lodge north of Karlstejn, Bohemia is the most diversified Bivalvia community in the Silurian of the Prague Basin. The lower Gorstian tuffaceous limestones, with more than 202 benthic and nektobenthic known species, represent the most fossiliferous Silurian level in the Prague Basin. The Janicula potens Community shows close palaeogeographic relationships with the upper Wenlock, Racine Formation reefs of Wisconsin and Illinois (North America), Silurian of Gotland and Dalarna (Sweden), Maine (North America), and Nova Scotia (Canada).