Tropidogyne lobodisca sp. nov., a third species of the genus from mid-Cretaceous Myanmar amber
DOI :
https://doi.org/10.17348/jbrit.v13.i2.798Résumé
The fossil flower described here is the third species of Tropidogyne to have been collected from mid-Cretaceous amber deposits in the Hukawng Valley of northwestern Myanmar. The flower of Tropidogyne lobodisca differs from the 2 previously described species, T. pikei and T. pentaptera, in lacking stamens and having a 5-lobed nectar disc covering the apex of the ovary. Its 2 slender, curved, attenuate styles are like those of T. pentaptera in being stigmatic along the adaxial surface. The new species has 5 spreading, reticulately-veined sepals, a generic character of Tropidogyne. An unusual, probably teratological, feature is the presence of 2 sepal-like staminodes on one side of the flower, inserted at the base of the nectar disc where stamens would otherwise be found. The inferior portion of the pistil is obconic, with 5 distinct veins that connect to the mid-nerves of the sepals.
Références
Barnes, R.W. & R.S. Hill. 1999. Ceratopetalum fruits from Australian Cainozoic sediments and their significance for petal evolution in the genus. Austral. Syst. Bot. 12:635–645.
Barnes, R.W., R.S. Hill, & J.C. Bradford. 2001. The history of Cunoniaceae in Australia from macrofossil evidence. Austral. J. Bot. 49:301–320.
Bradford, J.C., H.C.F. Hopkins, & R.W. Barnes. 2004. Cunoniaceae. In: K. Kubitzki, ed. The families and genera of vascular plants. Springer Verlag, Berlin, Germany. 6:91–111.
Chambers, K.L., G.O. Poinar, Jr., & R. Buckley. 2010. Tropidogyne, a new genus of Early Cretaceous eudicots (Angiospermae) from Burmese amber. Novon 20:23–29.
Cohen, K.M., S. Finney, & P.L. Gibbard. 2013. International Chronostratigraphic Chart. International Commission on Stratigraphy. www.stratigraphy.org
Cruickshank, R.D. & K. Ko. 2003. Geology of an amber locality in the Hukawng Valley, northern Myanmar. J. Asian Earth Sci. 21:441–455.
Dickison, W.C. 1989. Comparisons of primitive Rosidae and Hamamelidae. In: P.R. Crane and S. Blackmore, eds. Evolution, systematics, and fossil history of the Hamamelidae. 1:47–73.
Gandolfo, M.A. & E.J. Hermsen. 2017. Ceratopetalum (Cunoniaceae) fruits of Australasian affinity from the early Eocene Laguna del Hunco flora, Patagonia, Argentina. Ann. Bot. 119:507–516.
Kooyman, R.M., P. Wilf, V.D. Barreda, R.J. Carpenter, G.J. Jordan, J.M. Kale Sniderman, A. Allen, T.J. Brodribb, D. Crayn, T.S. Field, S.W. Laffan, C.H. Lusk, M. Rossetto, & P.H. Weston. 2014. Paleo-Antarctic rainforest into the modern Old World tropics: The rich past and threatened future of the “southern wet forest survivors.” Amer. J. Bot. 101:2121–2135.
Poinar, G.O., Jr. 2018a. Burmese amber: Evidence of Gondwanan origin and Cretaceous dispersion. Histor. Biol. 2018:1–6.
Poinar, G.O., Jr. 2018b. Mid-Cretaceous angiosperm flowers in Myanmar amber. In: B. Welch & M. Wilkerson, eds. Recent advances in plant research. Nova Science Publishers, New York, U.S.A. Pp. 187–218.
Poinar, G.O., Jr. & K.L. Chambers. 2017. Tropidogyne pentaptera sp. nov., a new mid-Cretaceous fossil angiosperm flower in Burmese amber. Palaeodiversity 10:135–140.
Poinar, G.O., Jr. & K.L. Chambers. 2018a. Endobeuthos paleosum gen. et sp. nov., fossil flowers of uncertain affinity from mid-Cretaceous Myanmar amber. J. Bot. Res. Inst. Texas 12:133–139.
Poinar, G.O., Jr. & K.L. Chambers. 2018b. Fossil flowers of Lachnociona camptostylus sp. nov., a second record for the genus in mid-Cretaceous Myanmar amber. J. Bot. Res. Inst. Texas 12:655–666.
Poinar, G.O., Jr. & K.L. Chambers. 2019a. Dispariflora robertae gen. et sp. nov., a mid-Cretaceous flower of possible Lauralean affinity from Myanmar amber. J. Bot. Res. Inst. Texas 13(1):173–183.
Poinar, G.O., Jr. & K.L. Chambers. 2019b. Strombothelya gen. nov., a fossil angiosperm with two species in mid-Cretaceous Myanmar amber. J. Bot. Res. Inst. Texas 13(2):XXX–XXX.
Poinar, G.O., Jr. & K.L. Chambers. 2019c. Dasykothon leptomiscus gen. et sp. nov., a fossil flower of possible Lauralean affinity from Myanmar amber. J. Bot. Res. Inst. Texas 13(2):XXX-XXX.
Poinar, G.O., Jr., G.J.B. Lambert, & Y. Wu. 2007. Araucarian source of fossiliferous Burmese amber: Spectroscopic and anatomical evidence. J. Bot. Res. Inst. Texas 1:449–455.
Rozefelds, A.C. & R.W. Barnes. 2002. The systematic and biogeographical relationships of Ceratopetalum (Cunoniaceae) in Australia and New Zealand. Int. J. Pl. Sci. 163:651–673.
Shi, G., D.A. Grimaldi, G.E. Harlow, J. Wang, M. Yang, W. Lei, Q. Li, & X. Li. 2012. Age constraint on Burmese amber based on U-Pb dating of zircons. Cretaceous Res. 37:155–163.
Sokol, J. 2019. Troubled treasure. Science 364:722–729.
