Rugose corals across the Early-Middle Devonian boundary in southern Belgium

In southern Belgium, the Emsian-Eifelian Boundary falls within the uppermost part of Moulin de la Foulerie Formation (Eau Noire Member), and is overlain by the lower Eifelian Couvin Formation (Villers-la-Tour and Petigny members). The Emsian part of the Eau Noire Member mostly comprises bioclastic limestone and calc-shale alternations whereas the Eifelian part consists of coral-stromatoporoid biostromes and siltstone. All these units are relatively rich in macrofauna, including locally abundant rugose corals. The taxonomic revision of the rugose coral collected below and above the boundary led to the identification of 28 species in 19 genera. Coral species previously described by H.H. Tsien are here re-described and their diagnoses are amended. The Emsian coral fauna is almost entirely composed of large solitary corals dominated by species of Acanthophyllum and Nardophyllum, associated with Calceola, Digonophyllum, Mesophyllum, and Tabulophyllum as well as the smaller corals Kunthia, Stringophyllum, and putative Chostophyllum; Microplasma is the only colonial genus recorded in the upper part of the Eau Noire Member. Undissepimented solitary corals are represented by Adradosia, Metriophyllum and Neaxon. The lower Eifelian yields Digonophyllum, Grypophyllum, Lekanophyllum, Nardophyllum, and Zonophyllum, as well as Adradosia and the colonial Sociophyllum. A new species of Sociophyllum is described from the basal Villers-la-Tour Member. No significant faunal change occurs across the Lower-Middle Devonian boundary, but the extinction of Tabulophyllum lissingenensis and Nardophyllum originale is located at the base of partitus conodont Zone. The coral association is similar in the Ardennes and Eifel Hills, though differences exist. Emsian coral assemblages from Brittany, the Cantabrian Mountains, the Montagne Noire and the Carnic Alps are very different, notably with the occurrences of colonial genera and endemic taxa.