Am. J. Bot.
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(American Journal of Botany. 1999;86:1200-1206.)
© 1999 Botanical Society of America, Inc.

Paleoazolla, a new heterosporous fern from the Upper Cretaceous of Argentina1

Ana Archangelsky 2,3 , Carlie J Phipps 3 , Thomas N Taylor 3 and Edith L Taylor 3

2Museo Paleontológico E. Feruglio, 9 de Julio 655, 9100 Trelew (Chubut), Argentina; 3Department of Ecology and Evolutionary Biology and the Natural History Museum and Biodiversity Research Center, University of Kansas, Lawrence, Kansas 66045

Megaspore and microspore massulae of Paleoazolla patagonica gen. et sp. nov. are described from the Upper Cretaceous of La Colonia Formation, Chubut Province, Argentina. The new fern possesses megaspore complexes with three to four glochidiate floats attached directly to the megaspore; a columella-like structure appears to be absent. The megaspore wall consists of a two-layered exine that is smooth to irregularly perforate, a two-layered perine with a spongy, densely packed endoperine, and a loosely organized exoperine. Infrafilosum hairs cover the exoperine. Microspore massulae are irregular in size and shape and bear multibarbed glochidia that generally have anchor-shaped tips. A comparison with other azollaceous and salviniaceous genera, particularly Azolla, is provided, together with a discussion of some evolutionary trends within the family.

Key Words: Argentina • Azollaceae • heterosporous ferns • Paleoazolla patagonica • Upper Cretaceous






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