The equisetalean genus Cruciaetheca nov. from the Lower Permian of Patagonia, Argentina.

CÚNEO, RUBÉN; ESCAPA, IGNACIO

INTERNATIONAL JOURNAL OF PLANT SCIENCES

UNIV CHICAGO PRESS

Lugar: Chicago; Año: 2006 vol. 167 p. 167 - 177

1058-5893

The new genus Cruciaetheca (Equisetales, Sphenopsida) is described from the R ́ıo Genoa Formation, Lower Permian of Chubut Province, Argentina. Ramified, whorled vegetative axes terminally bearing leaf whorls of the Phyllotheca type characterize this genus; some last-order axes bear fertile internodes with whorls of cruciate sporangiophores between unmodified leaf whorls. We describe three species, Cruciaetheca patagonica (Feruglio) Cu ́ neo et Escapa nov. comb., Cruciaetheca feruglioi Cu ́ neo et Escapa nov. sp., and Cruciaetheca genoensis Cu ́ neo et Escapa nov. sp., that are diagnosed from vegetative and reproductive features. The new material is compared with other Paleozoic equisetaleans from different geographical regions. We reevaluate the use of the genus Phyllotheca in light of finding Phyllotheca foliar whorls associated with completely distinct reproductive characters. The systematic position of Cruciaetheca is discussed as well as the significance of its cruciate sporangiophores and other characters.