The Carboniferous Gondwanan lycophyte Bumbudendron, revisited

The type material of Bumbudendron is reviewed in the light of current knowledge about fossil lycophytes. The bark is characterized having cushions with an infrafoliar bladder and a ligule. The variation in leaf bases and leaf scars and their presence may not only depend on the plant’s age or position on the stem, but also the plant’s preservation. The diagnosis of the genus is emended to include the presence of a ligule and a ligule pit in sterile and fertile leaves, the presence or absence of a preserved leaf scar, and variations in size and shape of the cushions resulting from preservation. Bumbudendron nitidum is here regarded as a synonym of B. millanii, the latter name having priority. In this concept, genus Bumbudendron comprises five species: B. paganzianum and B. millanii (Carboniferous of Argentina and Brazil), B. versiforme (Carboniferous and Lower Permian of Argentina and Uruguay), B. patagonicum (Permian of Argentina), and B. peruvianum (Lower Carboniferous of Peru). A review of the species of lycophytes from India, Niger, Ghana, and Egypt is suggested to determine whether they are assignable to Bumbudendron, and thus to define the geographic range of this genus.