First South American Agathis (Araucariaceae), Eocene of Patagonia

WILF PETER; ESCAPA I.; CÚNEO RUBEN; KOOYMAN ROBERT; JOHNSON, K. R.; ARI IGLESIAS

AMERICAN JOURNAL OF BOTANY

BOTANICAL SOC AMER INC

Lugar: St. Louis; Año: 2014 vol. 101 p. 156 - 179

0002-9122

* Premise of the study: Agathis is an iconic genus of very large, ecologically important,and economically valuable conifers that ranges over lowland to upper montanerainforests from New Zealand to Sumatra. Exploitation of its timber and copal hasgreatly reduced its numbers. The early fossil record of Agathis comes entirely fromAustralia, often presumed to be its area of origin.* Methods: We report abundant macrofossils of Agathis vegetative and reproductiveorgans, from early and middle Eocene rainforest paleofloras of Patagonia, Argentina.The leaves were formerly assigned to the New World cycad genus Zamia.*Key results: Agathis zamunerae sp. nov. is the first South American occurrence andthe most complete representation of Agathis in the fossil record. Its morphologicalfeatures are fully consistent with the living genus. The most similar living speciesphenetically is A. lenticula, endemic to lower montane rainforests of northern Borneo.*Conclusions: Agathis zamunerae sp. nov. demonstrates the presence of modernaspectAgathis by 52.2 Ma and vastly increases the early range and possible areas oforigin of the genus. The revision from Zamia breaks another link between the Eoceneand living floras of South America. Agathis was a dominant, keystone element of thePatagonian Eocene floras, alongside numerous other plant taxa that still associate withit in Australasia and southeast Asia. Agathis extinction in South America was anintegral part of the transformation of Patagonian biomes over millions of years, but theliving species are disappearing from their ranges at a far greater rate.