The Mesozoic scleractinian genus Adelocoenia (Stylinidae) and its Jurassic species

Abstract

The genus Adelocoenia ORBIGNY, 1849, is revised and a neotype is designated for its type species Astrea castellum MICHELIN, 1844. For various reasons that lie in the taxonomic history of scleractinian corals, it has become a difficult task to reliably assign Mesozoic corals having the combined features of plocoid corallite integration and the absence of a columella. Therefore, many such genera are in need of revision, one of which is Adelocoenia. In addition to the revision of the type species, Jurassic species grouped within Adelocoenia are revised using type material when it was possible. Many new synonymies are proposed based mainly on characters such as symmetry and dimensions of skeletal features. Another consequence is that most species previously grouped with Pseudocoenia ORBIGNY are transferred to Adelocoenia. Furthermore, we present a clarified view of the paleogeographical and stratigraphical distributional patterns of the genus Adelocoenia, according to which Adelocoenia had its first appearance during the Early Jurassic, represented by a single specimen known from the Sinemurian of France. Subsequently, this genus had a significant increase in both distribution and diversity during the Middle Jurassic. The pinnacle of its success followed in the Late Jurassic during which Adelocoenia had its greatest morphological disparity and taxonomical diversity, and its largest geographical distribution. The genus survived in the Cretaceous record. Throughout its history, Adelocoenia predominantly occurred in inner platform environments that were located in low latitudes.