A new species of Early Devonian Pleurodictyum Goldfuss, 1829 (Anthozoa, Tabulata) from the historical fossil site of Rates (NW Portugal): palaeoecological and palaeoenvironmental considerations

Originally described by Goldfuss in 1829, the tabulate corals assigned to genus Pleurodictyum are one of the typical elements of the Early Devonian palaeofaunas of Portugal, mentioned since the late nineteenth century. With a few exceptions, all findings have been classified as P. problematicum, despite several morphological differences that suggest a possible existence of other species. Based on new material collected from the historical fossil site of Rates (Póvoa de Varzim, NW Portugal) with a fossil assemblage dated to the Pragian‒Emsian (Early Devonian), a new species of Pleurodictyum is here described, which is preserved as internal moulds in yellowish shales. Named as Pleurodictyum nerydelgadoi sp. nov. in honour of Nery Delgado, an important pioneer of Portuguese geology, it differs from the other representatives of the genus by the number of corallites in relation to the diameter of the coral, as well as in the morphology of the corallites and their calicinal bottoms. This new species is interpreted as a passive suspension-feeder adapted to hard substrates in a shallow marine, low energy, well-oxygenised and low turbidity palaeoenvironment with fine-grained sedimentation and mixoeuhaline conditions.