Pennsylvanian brachiopods from the Geumcheon-Jangseong formation, Pyeongan supergroup, Taebaeksan Basin, Korea

We provide the first detailed systematic taxonomy and paleoecological investigation of late Paleozoic brachiopod faunas from Korea. Specifically, we focus on the brachiopods from the Geumcheon-Jangseong Formation, the lower part of the Pyeongan Supergroup in the Taebaeksan Basin. The formation yields a variety of marine invertebrate fossils, including brachiopods, molluscs, echinoderms, corals, fusulinids, and conodonts. Diverse brachiopods are described from six siliciclastic horizons of the formation at three localities, including 23 species belonging to 20 genera with two new species: <i>Rhipidomella parva </i>n. sp. and <i>Stenoscisma wooi</i> n. sp. Three brachiopod assemblages of the late Moscovian (Pennsylvanian) age are recognized based on their species compositions and stratigraphic distributions, namely the <i>Choristites,</i> <i>Rhipidomella,</i> and <i>Hustedia a</i>ssemblages. The brachiopod faunal composition varies within each assemblage as well as between the Assemblages, most likely reflecting local paleoenvironmental and hence paleoecological differences. The <i>Choristites</i> Assemblage includes relatively large brachiopods represented by <i>Derbyia, Choristites,</i> and <i>Stenoscisma </i>and may have inhabited open marine to partly restricted marine environments, whereas the <i>Rhipidomella</i> and <i>Hustedia</i> Assemblages consist of a small number of small-sized brachiopods living in lagoonal environments. The <i>Choristites</i> Assemblage shows a close affinity with Moscovian brachiopod assemblages in the eastern Paleo-Tethys regions, especially the <i>Brachythyrina lata–Choristites yanghukouensis–Echinoconchus elegans</i> Assemblage of North China, whereas the <i>Rhipidomella </i>and <i>Hustedia</i> assemblages both exhibit strong endemism.