Abstract Detail

Paleobotany

Andruchow Colombo, Ana [1], Rossetto-Harris, Gabriella [2], Brodribb, Tim [3], Gandolfo, Maria [4], Wilf, Peter [5].

A new species of Acmopyle (Podocarpaceae) with preserved accessory transfusion tissue from the early Eocene of Argentinean Patagonia.

Acmopyle is one of the 18 extant genera of the conifer family Podocarpaceae. The genus has two extant species with small rainforest ranges, A. pancheri (New Caledonia, Near Threatened) and A. sahniana (Fiji, Critically Endangered), along with a rich fossil record in Australia since the Paleocene and a few prior reports from Antarctica and South America. Here, we report a new fossil species of Acmopyle from the early Eocene of Laguna del Hunco (52.2 Ma), Patagonia, Argentina, based on 41 compression specimens of leafy shoots (expanded photosynthetic units). The new fossil taxon is heterophyllous like the extant members of the genus, presenting three distinct leaf types: scale-like leaves that are mostly bifacially flattened; transitional leaves that are tetragonal in cross-section to bilaterally flattened; and mature, highly coriaceous, robust and expanded leaves that are bilaterally flattened and show a two-ranked secondary arrangement over their branches. The new species uniquely preserves accessory transfusion tissue (ATT, an extra-venous water conducting tissue), an important physiological adaptation of extant Acmopyle, as well as possible reproductive buds. To test the placement of the new Patagonian Acmopyle, we included it in a total evidence phylogenetic analysis, together with extant and extinct members of the families Podocarpaceae and Araucariaceae. The fossil species is recovered in a polytomy with the two extant Acmopyle species. Additionally, we report herbivory damage, including margin feeding (DT12), apex feeding (DT13), hole feeding (DT01), and circular punctures (DT47). The presence of Acmopyle in the early Eocene of Argentina is significant because of the previously demonstrated drought intolerance in the genus, which stems from the high collapsing risk of the ATT; thus, the new fossils provide physiologically grounded evidence of the wet rainforest environments of Patagonia during the early Eocene Climatic Optimum and final stages of Gondwana.

1 - Cornell University, LH Bailey Hortorium, Plant Biology Section, School of Integrative Plant Science, 512 Mann Library, Ithaca, NY, 14853, USA
2 - Pennsylvania State University, Department of Geosciences, University Park, PA, 16802, USA
3 - University of Tasmania, School of Biological Sciences, Sandy Bay, Tasmania, 7001, Australia
4 - Cornell University, L.H. Bailey Hortorium, Section Of Plant Biology, 410 Mann Library Building, Ithaca, NY, 14853.0, United States
5 - Pennsylvania State University, Geosciences, 537 Deike Bldg., University Park, PA, 16802.0, United States

Keywords:
Conifers
Early Eocene climatic optimum
Laguna del Hunco
Patagonia
rainforest
total evidence phylogeny
Podocarpaceae
Acmopyle
Eocene.

Presentation Type: Oral Paper
Number:
Abstract ID:218
Candidate for Awards:None