Ginkgoites patagonica (Berry) comb. nov. from the Eocene of Patagonia, Last Ginkgoalean Record in South America Author(s): Liliana Villar de Seoane, N. Rubén Cúneo, Ignacio Escapa, Peter Wilf and María A. Gandolfo, Source: International Journal of Plant Sciences, (-Not available-), p. 000 Published by: The University of Chicago Press Stable URL: http://www.jstor.org/stable/10.1086/680221 . Accessed: 24/02/2015 19:49 Your use of the JSTOR archive indicates your acceptance of the Terms & Conditions of Use, available at . http://www.jstor.org/page/info/about/policies/terms.jsp . JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact [email protected]. The University of Chicago Press is collaborating with JSTOR to digitize, preserve and extend access to International Journal of Plant Sciences. http://www.jstor.org This content downloaded from 128.118.175.245 on Tue, 24 Feb 2015 19:49:36 PM All use subject to JSTOR Terms and Conditions Int. J. Plant Sci. 176(4):000–000. 2015. q 2015 by The University of Chicago. All rights reserved. 1058-5893/2015/17603-00XX$15.00 DOI: 10.1086/680221 GINKGOITES PATAGONICA (BERRY) COMB. NOV. FROM THE EOCENE OF PATAGONIA, LAST GINKGOALEAN RECORD IN SOUTH AMERICA Liliana Villar de Seoane,1,* N. Rubén Cúneo,† Ignacio Escapa,† Peter Wilf,‡ and María A. Gandolfo§ *División Paleobotánica, Museo Argentino de Ciencias Naturales “Bernardino Rivadavia,” Av. Angel Gallardo 470 (1405), Buenos Aires, Argentina; †Museo Paleontológico “Egidio Feruglio,” Av. Fontana 140 (9100), Trelew, Chubut; ‡Department of Geosciences, Pennsylvania State University, University Park, Pennsylvania, USA; and §School of Integrative Plant Science, Cornell University, Ithaca, New York, USA Editor: Michael Dunn Premise of research. The ginkgophytes are an ancient group of gymnosperms with a long history starting during the late Paleozoic and reaching the present with the unique species Ginkgo biloba L. In order to better characterize the early and middle Eocene (ca. 52.2 and 47.7 Ma) leaf species Ginkgo patagonica Berry from northwest Patagonia, Argentina, new specimens were studied, focusing on their morphological and anatomi- cal characters. Methodology. The specimens were studied with LM, epifluorescence, SEM, and TEM. Pivotal results. The diagnosis of the species Ginkgoites patagonica comb. nov. is enlarged to include anatomical and ultrastructural epidermal characters. Herein, the species Ginkgo patagonica is shown to have characteristics that clearly separate it from the genus Ginkgo L., and it is therefore recombined to the genus Ginkgoites Seward. Conclusions. Eocene Ginkgoites patagonica was present in plant communities, and it is the last repre- sentative of a still poorly understood southern ginkgophyte lineage that was distinct from the ancestors of G. biloba of the Northern Hemisphere. Keywords: Ginkgoales, cuticles, early-middle Eocene, Patagonia, Argentina. Introduction only on foliar characters. Discussions on this matter date to the late nineteenth century (see Watson et al. 1999, among The ginkgophytes are an ancient group of gymnosperms others), and as a result, in order to deal with the prolific rec- with a long history starting during the late Paleozoic and ord of Ginkgo-like leaves, Seward (1919) erected the genus reaching the present with the unique species Ginkgo biloba L. Ginkgoites to differentiate many fossil leaves from the mod- (Taylor et al. 2009). Their origin has been associated with ern species Ginkgo biloba. Nevertheless, the morphological Permian families such as the Trichopytiaceae and the Dicra- boundaries of Seward’s concept were not very precise. Debate nophyllaceae, from which true ginkgoaleans are thought to continued on this matter of whether to use other generic fossil have evolved during the Mesozoic (Archangelsky and Cúneo names or the genus Ginkgo for isolated fossil leaves (see, e.g., 1990; Stewart and Rothwell 1993; Villar de Seoane 1997; Del Harris and Middleton 1974). Some of these disagreements were Fueyo and Archangelsky 2001; Crane 2013; Del Fueyo et al. settled when Ginkgo-like leaves, including Ginkgoites, were 2013). found associated with reproductive structures very different Based on the limited record of reproductive organs, the ge- from those of G. biloba, for example, in Yimaia, Karkenia, and nus Ginkgo L. can be traced back into the Middle Jurassic even Ginkgo, demonstrating a larger past generic diversity (see (Zhou and Zhengh 2003). However, an earlier origin is hy- Del Fueyo and Archangelsky 2001; Zhou et al. 2002, 2012; pothetically possible when considering the high abundance of Zhou and Zheng 2003; see below for additional discussion). isolated Ginkgo-like leaves found in several Permian forma- Herein, a complete morphological, anatomical, and ultra- tions of Argentina (Feruglio 1933, 1942; Cúneo 1987). Unfor- structural cuticle study from new and historic specimens of tunately, there are no methods for attributing isolated Ginkgo- Ginkgo patagonica Berry (1935, 1938) from the Eocene of Pa- like leaves to the living genus Ginkgo with confidence based tagonia is presented. Based on these remains, the species is more properly recombined to the extinct genus Ginkgoites, and its diagnosis is expanded by adding new epidermal characters. 1 Author for correspondence; e-mail: [email protected]. Additionally, hypotheses regarding possible causes for the dis- Manuscript received June 2014; revised manuscript received November 2014; appearance of the ginkgophyte clade from the Southern Hemi- electronically published February 18, 2015. sphere are suggested. 000 This content downloaded from 128.118.175.245 on Tue, 24 Feb 2015 19:49:36 PM All use subject to JSTOR Terms and Conditions 000 INTERNATIONAL JOURNAL OF PLANT SCIENCES The Ginkgophyte Fossil Record from Tufolitas Laguna del Hunco (Chubut Province) by describ- Southern South America ing the epidermis of several leaves of Ginkgo patagonica us- ing LM. In Argentina, the ginkgophytes, represented by vegetative and reproductive structures, show a continuous record since Carboniferous times. Interestingly, they were never the dom- Material and Methods inant component in any plant community (Del Fueyo et al. 2013). Material The leaf genera Ginkgoites Seward and Ginkgophyllum Specimens were collected from two different localities (fig. 1). (Saporta) Neuburg occur in Carboniferous and Permian strata Geographic and stratigraphic data have been previously given from Patagonia (Feruglio 1933, 1942; Cúneo 1987; Escapa by Wilf et al. (2003, 2005). Specimens from the Laguna del and Cúneo 2003) and northwest of Argentina (Archangelsky Hunco locality in northwestern Chubut Province were collected and Arrondo 1974; Archangelsky and Leguizamón 1980). The from lacustrine caldera sediments belonging to the Tufolitas three Patagonian Permian species, Ginkgoites eximia (Feruglio) Laguna del Hunco (Aragón and Mazzoni 1997). Based on the Cúneo, Ginkgoites crassipes (Feistmantel) Feruglio, and Gink- 40Ar-39Ar ages of three intercalated ash layers aligned with goites feruglioi (Feruglio) Cúneo, look almost identical to mod- two paleomagnetic reversals, this unit is currently assigned ern Ginkgo leaves (Feruglio 1933; Cúneo 1987; Rothwell and to the early Eocene. The most reliable datum is a 40Ar-39Ar age Holt 1997). on sanidine from a tuff yielding a recently recalibrated age During the Triassic, Ginkgoites became more diverse with of 52.2 5 0.22 Ma (Wilf et al. 2003, 2005; Wilf 2012). The several taxa inhabiting Patagonia, such as Ginkgoites dutoitii Laguna del Hunco ginkgophyte leaves are exquisitely pre- Anderson et Anderson, Ginkgoites palmate (Ratte) Gnaedin- served and occur in low percentages in a megaflora domi- ger et Herbst, and Ginkgoites waldeckensis (Anderson et An- nated by dicot leaves and secondarily by conifers (Wilf et al. derson) Gnaedinger et Herbst, all representing leaf impressions 2005). Additional specimens were recently exhumed at the Río from the El Tranquilo Group, Santa Cruz Province (Azcuy and Pichileufú locality in lacustrine deposits of the La Huitrera Baldoni 1990; Gnaedinger and Herbst 1999). Records from Formation that crops out in southwestern Río Negro Province. other areas of Argentina include Ginkgoites truncata Frenguelli Volcanic tuffs immediately above the plant fossils yielded a (1946) from the Potrerillos Formation, Mendoza Province. high-precision 40Ar-39Ar age that was recently recalibrated to The oldest Argentinean record of Ginkgo-like cutinized 47.5 5 0.05 Ma, approximately 4.5 Myr younger than the leaves is the species Ginkgo taeniata Geinitz from the Lower fossil lake beds of the Tufolitas Laguna del Hunco (Wilf et al. Jurassic Paso Flores Formation, Neuquén Province, and it was 2005; Wilf 2012). The ginkgophyte leaves at Río Pichileufú described as having amphistomatic leaves that are divided also occur as a minor component of a highly diversified dicot- into four to eight lobes (Frenguelli 1937). In lower Cretaceous dominated taphoflora (Berry 1938; Wilf et al. 2005). strata, ginkgophyte remains are relatively more common and In this article, several specimens of Ginkgo patagonica were fi diverse in Patagonia. In the Aptian sediments of the An teatro analyzed: (1) the original specimens from Río Pichileufú de- de Ticó Formation (Baqueró