A New Fossil Wood of Koelreuteria (Sapindaceae) from the Pliocene of China and Remarks on the Phytogeographic History of Koelreuteria

Home , Koelreuteria, Koelreuteria bipinnata, Xanthoceras

IAWA Journal, Vol. 33 (2), 2012: 301–307

A new fossil wood of Koelreuteria (Sapindaceae) from the Pliocene of China and remarks on the phytogeographic history of Koelreuteria

Ye-Ming Cheng1,*, Ya-Fang Yin2, R.C. Mehrotra3 and Cheng-Sen Li4

SUMMARY Koelreuteria yuanmouensis sp. nov. (Sapindaceae) is described from the Pliocene fluvio-lacustrine rocks of Hutiaotan Earth Forest, Yuanmou Basin, Yunnan, China. This is the first report of fossilKoelreuteria wood from Asia. The history of the genus is reviewed. Fruits and leaves of the genus have been reported from the Paleocene onwards in Asia, North America, and Europe, with the genus becoming restricted to East Asia during the Neogene. Key words: Fossil wood, Koelreuteria, Neogene, Yuanmou Basin, phytogeography. INTRODUCTION

Today the genus Koelreuteria, family Sapindaceae, comprises three species. K. bipinnata Franchet, K. elegans Laxm. and K. paniculata Laxm., native to East Asia, with K. elegans subsp. elegans perhaps occurring in Fiji (Xia & Gadek 2007). Koelreuteria has a Tertiary fossil record indicating that it was widely distributed in North Ameri- ca (USA), Europe (Czech Republic, Far East of Russia) and East Asia (China, Japan) (Manchester 1999; Manchester et al. 2009). This paper describes a fossil wood resem- bling Koelreuteria from the Pliocene of Yunnan, China, providing additional information on the occurrence and characteristics of the genus during the Neogene.

Material and methods

The material for this study was collected from the Earth Forest (scenic spot) near Hut- iaotan (25° 50.64' N, 101° 45.45' E) of the Yuanmou County, Yunnan Province, China. The Earth Forest was formed by geological movement and soil erosion and mainly consists of fluvio-lacustrine rocks ranging from Pliocene to Pleistocene in age (Qian & Ling 1989). The Earth Forest strata are considered to be members one and two of the Lower Yuanmou Formation, with a paleomagnetic age of 3.4–2.5 Ma B.P. (Qian & Ling 1989; Qian & Zhou 1991). This study is based on two samples collected from

1) The Geological Museum of China, Xisi, Xicheng District, Beijing 100034, P.R. China; 2) Wood Anatomy and Utilization Group, Research Institute of Wood Industry, Chinese Academy of Forestry, No 1 of Dongxiaofu, Haidian District, Beijing 100091, P.R. China; 3) Birbal Sahni Institute of Palaeobotany, 53 University Road, Lucknow-226007, India; 4) State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Xiangshan, Haidian District, Beijing, 100093, P.R. China; *) Corresponding author [E-mail: [email protected]].

Downloaded from Brill.com10/02/2021 05:18:55PM via free access 302 IAWA Journal, Vol. 33 (3), 2012 a log that was approximately 40 cm in diameter. Slides were prepared by the standard method of cutting, grinding and polishing using different grades of carborundum powder (Hass & Rowe 1999). Thin sections were studied using a microscopic image analyzer (Olympus BX60 with DP72 digital collector). Slides of extant wood used for comparative studies are housed in the Wood Collection of the Research Institute of Wood Industry, Chinese Academy of Forestry. All fossil specimens and slides have been deposited in the Geological Museum of China, Beijing. Anatomical terms used in this paper follow the recommendations of the IAWA List of Microscopic Features for Hardwood Identification (IAWA Committee 1989).

Systematic description Family Sapindaceae Genus Koelreuteria Laxm. Species Koelreuteria yuanmouensis, Cheng, Yin, Mehrotra et Li, sp. nov. (Fig. 1) Specific diagnosis — Growth rings distinct. Wood ring porous. Earlywood vessels solitary and in radial multiples of 2–5 (mostly 2 or 3); latewood vessels in radial multiples and in small clusters. Tangential diameter of vessels range 26–200, mean 112 µm. Perforation plates simple. Intervessel pits alternate, 5–8 µm in size. Mean vessel element length 145–427 µm, mean 259 µm. Vessel-ray parenchyma pits similar to intervessel pits. Helical thickenings present only in narrow vessel elements of latewood. Rays 1–3(–4)-seriate, homocellular; 69–699 µm, mean 289 µm in height. Ray frequency 14–22/mm. Axial parenchyma predominantly paratracheal, five to ten cells per parenchyma strand. Septate fibers present. Solitary crystals often present in procumbent cells. Holotype – Two fragments obtained from one piece of trunk wood that measured approximately 40 cm in diameter and 60 cm in length (P2288, P2289). Locality – Hutiaotan Earth Forest, Yuanmou Basin, Yunnan Province, China. Horizon – Lower part of the Yuanmou Formation. Age – Pliocene. Etymology – The specific epithet is after the fossil locality. Repository – the Geological Museum of China, Beijing.

DISCUSSION Comparison with modern woods The following combination of features indicates this wood’s affinities are with the Sapindaceae: distinct growth rings, ring porous wood, earlywood vessels solitary and in radial multiples of 2–5 (mostly 2–3), latewood vessels in radial multiples and in small clusters, simple perforations, helical thickenings in narrow vessels, alternate intervessel pits, sparse axial parenchyma, homocellular narrow rays, and septate fibers (Metcalfe & Chalk 1950; Cheng et al. 1992; Li et al. 1995; Klaassen 1999; InsideWood 2004-onwards). Klaassen (1999) provides a key to identify 104 genera of the Sapin- daceae. According to this key only three genera of Sapindaceae, Koelreuteria Laxm., Sapindus L. and Xanthoceras Bunge, have ring porous to semi-ring porous wood.

Downloaded from Brill.com10/02/2021 05:18:55PM via free access Cheng Ye-Ming et al. — Pliocene wood of Koelreuteria from China 303

Figure 1. Koelreuteria yuanmouensis Cheng et al., sp. nov. (Sapindaceae). – A: Distinct growth rings and ring porous wood. TS. – B: Latewood vessels in radial multiples and clusters, TS. – C: Simple perforation plate. RLS. – D: Alternate intervessel pits. TLS. – E: Narrow vessels with helical thickenings (arrows). RLS. – F: Septate fibers (septum marked with an arrow). TLS. – G: Rays 1–3-seriate, crystal in a ray cell (arrow). TLS. – H: Homocellular rays composed of procumbent cells. RLS. — Scale bars: A = 1 mm; B = 200 µm; C, D, F = 50 µm; E = 20 µm; G, H = 100 µm.

Downloaded from Brill.com10/02/2021 05:18:55PM via free access 304 IAWA Journal, Vol. 33 (3), 2012

Figure 2. Extant Koelreuteria bipinnata Franchet (Sapindaceae) (CAFw10258, Guangxi Province, China). – A: Distinct growth rings and ring porous wood. TS. – B: Latewood vessels in radial multiples and clusters. TS. – C: Narrow vessels with helical thickenings, septate fibers. TLS. – D: Homocellular rays composed of procumbent cells. RLS. – E: 1–2-seriate rays. TLS. — Scale bars: A, B = 200 µm; C = 20 µm; D, E = 100 µm.

Sapindus differs as it has banded, aliform, and confluent parenchyma. Xanthoceras has non-septate fibers and helical thickenings in all the vessels. The fossil is similar to extant species of Koelreuteria in all characters except its rays are slightly wider, 1–3-seriate, than those of extant Koelreuteria whose rays are 1–2-seriate (mostly uni- seriate) (Fig. 2A–E). Earlywood vessels are mainly solitary in K. bipinnata Franchet (Fig. 2A–E) and K. elegans Laxm., whereas they are in irregular multiples of 2 or 3 in K. paniculata Laxm. (Li et al. 1995). In the fossil wood the earlywood vessels are solitary and in radial multiples.

Downloaded from Brill.com10/02/2021 05:18:55PM via free access Cheng Ye-Ming et al. — Pliocene wood of Koelreuteria from China 305

Comparison with fossil woods To date only two fossil woods with some similarities to Koelreuteria have been described. Sapindoxylon koelreuterioides Poole et Wilkinson is based on twig wood from the Eocene London Clay of southeast England; it was compared to both Nephelium and Koelreuteria (Poole & Wilkinson 1992). It differs from the wood described herein as it is diffuse porous with no evidence of helical thickenings. Koelreuteria sp. is from the Late Eocene Florissant Formation in Colorado, USA (Wheeler 2001). The Florissant fossil differs slightly from this Chinese wood as it has somewhat narrower vessels, fewer rays per mm and shorter rays. Other fossil woods of sapindaceous affinity (Gregoryet al. 2009) include: Djambi- oxylon Kräusel (1922), Sapindoxylon Kräusel (1922), Pometioxylon Prakash et Tripathi (1970), Matayboxylon Suguio et Mussa (1978), Euphorioxylon Awasthi et al. (1982), Schleicheroxylon Awasthi et al. (1982), and Isoschleicheroxylon Gottwald (1994). All differ from the fossil described herein in having diffuse porous wood.

The Tertiary phytogeographic history of Koelreuteria The oldest known fossil of Koelreuteria (fruit valves) is from the Paleocene of southern Primorye, Russia (Ablaev 2000). In North America, fossil fruits of Koel- reuteria have been described from the Middle Eocene of the Green River Formation (Manchester 1999), the Eocene of British Columbia (Dillhoff et al. 2005) and the Late Eocene Florissant Formation of Colorado (MacGinitie 1953, 1969; Manches- ter 2001). In Europe, records of this genus include fruits from the late Oligocene of Rott, Germany (Weyland 1937) and the Miocene of Randecker Maar, Germany (Rüffle 1963), Bohemia (Bůžek 1971) and Czech Republic (Kvaček et al. 2004; Teodoridis 2007). In Asia, a well preserved fossil fruit valve, Koelreuteria sp., from the Eocene Huadian flora of northeast Jilin, is the earliest unequivocal record of the genus from China (Manchester et al. 2005). A fruit assigned to Koelreuteria microcarpa Li from the Middle-Late Eocene of Liaoning (WGCPC 1978), was later determined to belong to Craigia of the Malvaceae (Kvaček et al. 2005). Other fruit valves are reported from the Miocene Shanwang flora of Shandong Province of China (Hu & Chaney 1940) and the Late Miocene Tatsumitoge flora of southwestern Honshu, Japan (Ozaki 1980). There are several records of fossil leaves of Koelreuteria from the Neogene of China, including K. macrocarpa Tao from the Early-Middle Miocene of Shandong (WGCPC 1978; Tao 1992), Koelreuteria sp. from the Late Miocene-Early Pliocene of Yunnan (Tao & Chen 1983), K. cf. integrifoliola Merr. from the Pliocene of Shanxi (Cao & Cui 1989), and K. bipinnata Franchet from the Pliocene- Pleistocene of Xinjiang (Guo & Gu 1993). The fossil record indicates that Koelreuteria had a wider distribution in the Northern Hemisphere during the Eocene and Oligocene. During the global cooling of the Neogene (Zachos et al. 2001), it evidently became restricted to China. According to Manchester et al. (2009) Eastern Asia with its special topographical features might have served as a Late Tertiary or Quaternary refugium for Koelreuteria.

Downloaded from Brill.com10/02/2021 05:18:55PM via free access 306 IAWA Journal, Vol. 33 (3), 2012

Acknowledgements

The authors are thankful to the National Natural Science Foundation of China (No. 31170206) and Chinese Academy of Forestry (No. CAFYBB2011005-2) for the financial support.

References

Ablaev, A.G. 2000. Paleogene biostratigraphy of the coastal region in South Primorye. Russian Academy of Sciences Far Eastern Branch, Pacific Institute of Oceanography, Vladivostok [in Russian]. Awasthi, N., J.S. Guleria & R.N. Lakhanpal. 1982. Two new fossil woods of Sapindaceae from the Tertiary of India. The Palaeobotanist 30: 12–21. Bůžek, Č. 1971. Tertiary flora from the northern part of the Pětipsy area (North-Bohemian Basin). Rozpravy Ústředni Ústavu Geolologického Prague 36: 1–118. Cao, J.X. & H.T. Cui. 1989. Research of Pliocene flora and palaeoenvironment of Yushe Basin on Shanxi Plateau, China. Sci. Geol. Sin. 4: 369–375. Cheng, J.Q., J.J. Yang & P. Liu. 1992. Chinese woods. Chinese Forestry Publishing House, Beijing [in Chinese]. Dillhoff, R.M., E.B. Leopold & S.R. Manchester. 2005. The McAbee flora of British Columbia and its relation to the Early-Middle Eocene Okanagan Highlands flora of the Pacific North- west. Can. J. Earth Sci. 42: 151–166. Gottwald, H.P. J. 1994. Tertiare Hölzer aus dem Chindwinn-Bassin in nordwestlichen Myanmar (Birma). Documenta Naturae, München 86: 1–90. Gregory, M., I. Poole & E.A. Wheeler. 2009. Fossil dicot wood names - an annotated list with full bibliography. IAWA J. Suppl. 6: 220 pp. Guo, S.X. & G.G. Gu. 1993. Fossil plants from calcareous tufa and palaeoenvironments in Ruoqiang, Xinjiang. Acta Palaeontol. Sin. 32: 82–87. Hass, H. & N.P. Rowe. 1999. Thin sections and wafering. In: T.P. Jones & N.P. Rowe (eds.), Fossil plants and spores: modern techniques: 76–81. Geological Society, London. Hu, H.H. & R.W. Chaney. 1940. A Miocene flora from Shantung Province, China. Palaeonto- logica Sinica New Series A, No.1: 1–147. IAWA Committee. 1989. IAWA list of microscopic features for hardwood identification.I AWA Bull. n.s. 10: 219–332. InsideWood. 2004-onwards. Published on the Internet. http://insidewood.lib.ncsu.edu/search [date of accession]. Klaassen, R. 1999. Wood anatomy of the Sapindaceae. IAWA J. Suppl. 2: 214 pp. Kräusel, R. 1922. Fossile Hölzer aus dem Tertiär von Süd-Sumatra. Beiträge zur Geologie und Paläontologie von Sumatra. No. 4. Verh. Geol.-Mijnbouwk. Gen. Nederl. en Koloniën - Geol. Ser. 5: 231–287. Kvaček, Z., M. Böhme, Z. Dvořák, M. Konzalová, K. Mach, J. Prokop & M. Rajchl. 2004. Early Miocene freshwater and swamp ecosystems of the Most Basin (northern Bohemia) with particular reference to the Bilina Mine section. J. Czech Geol. Soc. 49: 1–40. Kvaček, Z., S.R. Manchester & M.A. Akhmetiev. 2005. Review of the fossil history of Craigia (Malvaceae s.l.) in the northern hemisphere based on fruits and co-occurring foliage. In: M.A. Akhmetiev & A.B. Herman (eds.), Modern problems of Palaeofloristics, Palaeo- phytogeography, and Phytostratigraphy: 114–140. GEOS, Moscow. Li, B.Z., B. J.H. ter Welle & R.K.W.M. Klaassen. 1995. Wood anatomy of trees and shrubs from China. vii. Sapindaceae. IAWA J. 16: 191–215. MacGinitie, H.D. 1953. Fossil plants of the Florissant Beds, Colorado. Carnegie Institution of Washington Publication 599, Washington DC. 198 pp.

Downloaded from Brill.com10/02/2021 05:18:55PM via free access Cheng Ye-Ming et al. — Pliocene wood of Koelreuteria from China 307

MacGinitie, H.D. 1969. The Eocene Green River flora of northwestern Colorado and northeastern Utah. University of California Publications in Geological Sciences 83: 1–140. Manchester, S.R. 1999. Biogeographical relationships of North American Tertiary floras. Ann. Missouri Bot. Gard. 86: 472–522. Manchester, S.R. 2001. Update on the megafossil flora of Florissant, Colorado. Fossil flora and stratigraphy of the Florissant Formation, Colorado. In: E. Evanoff, K.M. Gregory-Wodzicki & K.R. Johnson (eds.), Fossil flora and stratigraphy of the Florissant Formation, Colorado. Proc. Denver Mus. Nature and Science Series 4: 137–161. Manchester, S.R., Z.D. Chen, B.Y. Geng & J.R. Tao. 2005. Middle Eocene flora of Huadian, Jilin Province, Northeastern China. 3. Acta Palaeobotanica 45: 3–26. Manchester, S.R., Z.D. Chen, A.M. Lu & K. Uemura. 2009. Eastern Asian endemic seed plant genera and their paleogeographic history throughout the Northern Hemisphere. J. Syst. Evol. 47: 1–42. Metcalfe, C.R. & L. Chalk. 1950. Anatomy of the dicotyledons. Clarendon Press, Oxford. Ozaki, K. 1980. Late Miocene Tatsumitoge flora of Tottori Prefecture, Southwest Honshu, Japan. III. Science Reports of the Yokohama National University Sec. 2, no. 27: 19–45. Poole, I. & H.P. Wilkinson. 1992. Two sapindaceous woods from the London Clay (Eocene) of southeast England. Rev. Palaeobot. Palynol. 75: 65–75. Prakash, U. & P.P. Tripathi. 1970. Fossil woods from the Tertiary of Hailakandi, Assam. The Palaeobotanist 18: 20–30. Qian, F. & X.H. Ling. 1989. Preliminary study on formation and pattern of Yuanmou Earth Forest. Chinese Sci. Bull. B 4: 412−418 [in Chinese]. Qian, F. & G.X. Zhou. 1991. Quaternary geology and palaeoanthropology of Yuanmou, Yun- nan, China. Science Press, Beijing: 222 pp. [in Chinese with English abstract]. Rüffle, L. 1963.D ie Obermiozäne Flora vom Randecker Maar. Paläontologische Abhandlungen 1 (3): 139–296. Suguio, K. & D. Mussa. 1978. Madeiras fosseis dos Aluviois Antigos do Rio Tieté, São Paulo. Bol. Inst. Geoci. Univ. São Paulo 9: 25–45. Tao, J.R. 1992. Study on the fossil flowers of angiosperms. Acta Bot. Sin. 34: 240–242. Tao, J.R. & M.H. Chen. 1983. Neogene flora of the south part of the watershed of Salween– Mekong–Yangtze rivers (the Linczan region), Yunnan. Exploration of Hengduan Mountain area. Beijing Publishing House of Sciences and Technology, Beijing, 1: 74–89 [in Chinese with English abstract]. Teodoridis, V. 2007. Revision of Potamogeton fossils from the Most Basin and their palaeoeco- logical significance (Early Miocene, Czech Republic). Bull. Geosci. 82: 409–418. Weyland, H. 1937. Beiträge zur Kenntnis der Rheinischen Tertiärflora.II . Erste Erganzungen und Berichtigungen zur Flora der Blatterkohle und des Polierschiefers von Rott im Siebengebirge. Palaeontographica B 83: 67–122. WGCPC – Writing Group of Cenozoic Plants of China. 1978. Cenozoic plants from China, Fossil plants of China, 3. Science Press, Beijing [in Chinese]. Wheeler, E.A. 2001. Fossil dicotyledonous woods from Florissant fossil beds National Monu- ment, Colorado. In: E. Evanoff, K.M. Gregory-Wodzicki & K.R. Johnson (eds.), Fossil flora and stratigraphy of the Florissant Formation, Colorado. Proc.D enver Mus. Nature and Science Series 4: 187–204. Xia, N.H. & P.A. Gadek. 2007. Sapindaceae. In: Z.Y. Wu, P.H. Raven & D.Y. Hong (eds.), Flora of China 12: 5–24. Missouri Botanical Garden Press, St. Louis, and Science Press, Beijing. Zachos, J., M. Pagani, L. Sloan, E. Thomas & K. Billups. 2001. Trends, rhythms, and aberrations in global climate 65 Ma to present. Science 292: 686–693.

Downloaded from Brill.com10/02/2021 05:18:55PM via free access