PAPUACEDRUS (CUPRESSACEAE) IN EOCENE PATAGONIA, A NEW FOSSIL LINK TO AUSTRALASIAN RAINFORESTS

P WILF; S. LITTLE; ARI IGLESIAS; M.C. ZAMALOA; GANDOLFO, M. A.; CÚNEO, N. R.; JOHNSON, K. R.

AMERICAN JOURNAL OF BOTANY

Botanical Society of America

Lugar: Stanford; Año: 2009 vol. 96 p. 2031 - 2047

0002-9122

The 51.9 Ma Laguna del Hunco (LH) and 47.5 Ma R í o Pichileuf ú (RP) fl oras from Patagonia, Argentina are unusually rich,angiosperm-dominated assemblages with living relatives in the low-latitude West Pacifi c, neotropics, and temperate southern latitudes.The diverse gymnosperms in these fl oras are important for Gondwanan biogeographic history and paleoclimatic interpretations.“ Libocedrus ” prechilensis Berry 1938 (Cupressaceae), previously known only from the holotype (RP), a vegetative branch,is revised here based on new material from both localities, including a seed cone attached to a shoot with cuticle (LH). Charactersof these fossils are diagnostic of monotypic Papuacedrus (highlands of New Guinea and Moluccas). Living P. papuana is mostabundant in cloud forests receiving up to 4 m rainfall annually, whereas Austrocedrus ( Libocedrus ) chilensis , the basis of comparisonwhen the fossil species was named, inhabits dry, cold steppe margins to mediterranean climates in southern South America.We establish Papuacedrus prechilensis comb. nov., which simultaneously invalidates a southern South American connection forthe fossil fl oras and reveals a link to West Pacifi c montane rainforests. Combined evidence indicates a biome similar to extantsubtropical, or tropical montane, rainforests that persisted for at least 4.4 Myr, linking elevated fl oral richness to abundantrainfall.