Paleocene flora from Seymour Island, Antarctica: revision of Dusén’s (1908) angiosperm taxa

Abstract

The Paleocene flora from Seymour Island, Antarctica, is one of the most diverse floras of this age in the Southern Hemisphere. First collected on the Swedish South Polar Expedition (1901–1903), it was described by Dusén in 1908 as having 87 leaf taxa. Forty-seven angiosperm taxa were described and/or illustrated. Many species are based on single specimens, and the flora has not been re-examined in its entirety since it was first described. This study is the first reassessment of the flora updating the original research using current methodologies, and permitting evaluation of the flora in the context of modern ideas on plant evolution and palaeogeography. This paper continues the revision of the material first studied by Dusén; a previous paper described the ferns and gymnosperms; here we describe the angiosperms. The revision is based on the original collections held at the Swedish Museum of Natural History, together with the first major new collections held at the British Antarctic Survey. Among the taxa recognized by Dusén, we recognize only three entire-margined and 11 tooth-margined angiosperms. This revision to 14 species notably lacks the two tropical elements originally described from the flora, Mollinedia seymourensis and Miconiiphyllum austral. Hence, its status as a ‘Mixed Flora’ comes into question and influences climatic interpretations based on Gondwanan floras. Anne-Marie Tosolini^∗ [[email protected]], Department of Earth Sciences, University of Leeds, Leeds LS2 9JT, UK, and Environmental Geoscience, Latrobe University, Victoria, 3086, Australia; David Cantrill [[email protected]], National Herbarium of Victoria, Royal Botanic Gardens Melbourne, Private Bag 2000, Birdwood Ave, South Yarra, Victoria, 3141, Australia; Jane Francis [[email protected]], Department of Earth Sciences, University of Leeds, Leeds LS2 9JT, UK. ∗Present address: School of Earth Sciences, The University of Melbourne, Victoria 3010, Australia. Received 5.5.2012; revised 13.12.2012; accepted 7.1.2012.

南极洲Seymour 岛古新世植物群:对Dusén(1908)的被子植物分类群的修正

南极洲Seymour岛的古新世植物群是南半球同年代分异度最高的植物群之一。第一次采集是在瑞典南极区远征(1901-1903)过程中,由Dusén描述了87个叶分类群。47个被子植物分类群被描述及/图示。很多种依据的是单一标本。自首次描述以来,该植物群还未曾以一个整体而被重新研究过。我们运用现代方法重新研究这个植物群并更新原始研究,使得在植物演化和古地理学的背景下重新对植物群进行审定。本文继续对Dusén 所研究的材料进行再研究;以前一篇文章描述了蕨类和裸子植物;我们在此描述被子植物。我们的工作基于保存在瑞典自然历史博物馆的初始采集品及保存在英国南极调查局的首批主要新采集品。在Dusén识别的分类群中,我们只识别出三种全缘和十一种齿缘被子植物。对这十四个种的再研究显然缺乏原先描述的两个热带分子:Mollinedia seymourensis 和Miconiiphyllum austral。因此,这个植物群被冠以“混杂植物群”显然有问题,会影响根据冈瓦纳植物群所进行的环境解释。

Key words:

• Paleocene
• Antarctica
• Gondwana
• polar
• leaf flora
• angiosperm
• foliar physiognomy

Acknowledgements

Funding of JEF, DJC and the postdoctoral position of A-M.T. was funded by the NERC–BAS Antarctic Funding Initiative grant GR3/G0001. All fieldwork to Antarctica was supported by this funding initiative, although specimens from many BAS trips to the region were also analyzed. We would like to thank Dr I. Poole and Crispin Day for helping to collect material in 1999, to Rob Scott in 2000, and also to past BAS (FIDS) geologists for their collections of the Cross Valley flora. Dr Richard Hunt is thanked for assistance with leaf architecture analysis, and drawing and photographic techniques. DJC would like to acknowledge that part of this work was supported when he was employed at the BAS and at the Swedish Museum of Natural History. The Swedish Museum of Natural History is thanked for giving assistance and access to the Nordenskjöld Collection. Two anonymous reviewers are acknowledged for helpful comments on the manuscript.