A new aquatic crustacean (Isopoda: Cymothoida) from the early Cretaceous of southern England and comparison with the Chinese and Iberian biotas

The first malacostracan crustacean is described and named from the English Wealden, Cymothoidana websteri gen. et sp. nov., a Cirolana-like, cymothoidan isopod. The problem of homoplastic convergence in somatic characters is discussed, and Cymothoidana is treated as a collective group (morphotaxon) under the International Code of Zoological Nomenclature for cirolanoid and cymothooid fossils which cannot be assigned to natural taxa on preservational grounds. The palaeoecology of early Cretaceous peracaridan malacostracans is considered, including the spelaeogriphaceans Liaoningogriphus from China (Jehol biota), and Spinogriphus from Spain (Las Hoyas Konservat-lagerstätte). There were probably no true stygobites, Spinogriphus perhaps a crenobite, but the colonisation of reduced salinity environments (Cymothoidana) and freshwater lakes (Liaoningogriphus) had commenced.