The nomenclature of fossil-taxa representing different preservational states: Lepidodendron as a case-study

The fossil-genus Lepidodendron is normally used for adpressions, casts and moulds of Palaeozoic arborescent lycophyte stems, but it has also sometimes been used for anatomically preserved stems and even whole-plant reconstructions. When used for anatomically preserved fossils, Lepidodendron is usually now restricted to the group of species allied to Lepidodendron hickii, but this results in confusion and potential disruption to the traditional use of the fossil-genus for non-anatomically preserved stems. The case is made for separate sets of fossil-genera for the anatomically and non-anatomically preserved stems, with the circumscription of Lepidodendron being limited to adpressions, casts and moulds. A new fossil-genus, Dimicheleodendron gen. nov., is proposed for the lycophyte stem petrifactions typified by Lepidodendron hickii.