Cuticles of Mariopteris occidentalis White nov emend. from the Middle Pennsylvanian of Oklahoma (USA), and a new type of climber hook for mariopteroid pteridosperms

Cuticles of Mariopteris occidentalis are described from the Desmoinesian (M iddle Pennsylvanian) of Oklahoma (USA). This species, like other marioptero ids, had a vine- to liana-like growth habit and climbed with specialized cl imber hooks. However, M. occidentalis is different from other mariopteroids in having small recurved hooks on the abaxial surfaces of the pinna axes. The diagnosis for M. occidentalis White 1899 is emended based on additional macroscopical observations and data on the epidermal anatomy; a lectotype is designated. M. occidentalis is compared with Pseudomariopteris cordato-o vata from the Stephanian and Autunian 'of Europe and North America, a taxon which is considered very similar and may be related. Although the two taxa indeed display similarities, significant evidence for a closer relationshi p could not be found. Finally, some features, e.g. marginal water pits and the stomatal structure, are considered with regard to their palaeoautecolog ical significance where they are interpreted as adaptations to special phys iological requirements of a vine- to liana-like life form. (C) 2001 Elsevie r Science B.V. All rights reserved.