Goryeocrinus pentagrammos n. gen. n. sp. (Rhodocrinitidae; Diplobathrida), the first record of camerate crinoid from the Middle Ordovician (Darriwilian) of South Korea (East Gondwana)

Goryeocrinus pentagrammos n. gen. n. sp. from the Jigunsan Formation of South Korea is described, which is the first diplobathrid record from Middle Ordovician (middle Darriwilian) of East Gondwana. Phylogenetic analyses suggest that G. pentagrammos is a member of the paraphyletic Rhodocrinitidae of the Diplobathrida and most closely related to Paradiabolocrinus from the Late Ordovician (Sandbian) of Laurentia. G. pentagrammos is characterized by having a pentameral, flat bowl-shaped calyx, conspicuous pentagrammatic ridge formed by bifurcated median ray ridge and pentagonal basal ridge, at least two interradials in the first row of regular interrays, and anitaxial ridge originating from CD interray but close to C ray radial, and lacking intrabrachials and interradials between secundibrachials. The occurrence of G. pentagrammos from South Korea (East Gondwana) drastically expands Ordovician paleogeographic range of the camerates which have otherwise been recorded from Laurentia, West Gondwana, Avalonia, and Baltica.