Zygadelphus aetheus gen. et sp. nov., an unusual fossil flower from mid-Cretaceous Myanmar amber
DOI:
https://doi.org/10.17348/jbrit.v13.i2.799Abstract
The flower described here as Zygadelphus aetheus gen. et sp. nov. was obtained from amber mines in Myanmar, preserved in marine sedimentary deposits dating to the mid-Cretaceous Period, ca. 99 My in age. The perianth consists of ca. 10 spirally arranged tepals that vary in size and shape. The stigmatic tips of two styles are visible, the remainder of the gynoecium being hidden from view by the crowding of stamens and perianth parts toward the center of the flower. There is a whorl of 4 stamens, the anthers of which have the feature, probably unique among angiosperms, of possessing a small but complete accessory stamen arising as an appendage on their dorsal surface. Anthers of both types of stamens are bilocular and dehisce by dorsally hinged valves. Presence of pollen in the accessory anthers indicates that they functioned in reproduction. Under the assumption that the fossil is not merely a teratological mutant in an otherwise normal-flowered species, it is here given taxonomic status as representing a peculiar type of floral development, now extinct, that existed during an earlier stage of angiosperm evolution.
Literaturhinweise
Cruickshank, R.D. & K. Ko. 2003. Geology of an amber locality in the Hukawng Valley, northern Myanmar. J. Asian Earth Sci. 21:441–455.
Endress, P.K. 1980. Floral structure and relationships of Hortonia (Monimiaceae). Pl. Syst. Evol. 133:199–221.
Endress, P.K. & L.D. Hufford. 1989. The diversity of stamen structures and dehiscence patterns among Magnoliidae. Bot. J. Linn. Soc. 100:45–85.
Kubitzki, K. 1993. Gomortegaceae. In: K. Kubitzki, J.G. Rohwer, & V. Bittrich, eds. The families and genera of vascular plants. Springer Verlag, Berlin, Germany. 2:318–320.
Pax, F. 1891. Monimiaceae and Hernandiaceae. In: A. Engler & K. Prantl, eds. Die natürlichen Pflanzenfamilien. Verlag Wilhelm Engelmann, Leipzig, Germany. III. 2:94–105, 126–129.
Perkins, J. & E. Gilg. 1901. Monimiaceae. In: A. Engler, ed. Das Pflanzenreich. Verlag Wilhelm Engelmann, Leipzig, Germany. IV. 101:1–122.
Philipson, W.R. 1993. Monimiaceae. In: K. Kubitzki, J.F. Rohwer, & V. Bittrich, eds. The families and genera of vascular plants. Springer Verlag, Berlin, Germany. 2:426–437.
Poinar, G.O., Jr. 2017. A mid-Cretaceous Lauraceae flower, Cascilaurus burmitis gen. et sp. nov., in Myanmar amber. Cretaceous Res. 71:96–101.
Poinar, G.O., Jr. 2018a. Burmese amber: Evidence of Gondwanan origin and Cretaceous dispersion. Hist. 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. 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. Setitheca lativalva gen. et sp. nov., a fossil flower of Laurales from mid-Cretaceous Myanmar amber. J. Bot. Res. Inst. Texas 12:643–653.
Poinar, G.O., Jr. & K.L. Chambers. 2018c. 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:xxx–xxx.
Poinar, G.O., Jr. & K.L. Chambers. 2019c. Tropidogyne lobodisca sp. nov., a third species of the genus from mid-Cretaceous Myanmar amber. J. Bot. Res. Inst. Texas 13: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.
Renner, S.S. 1999. Circumscription and phylogeny of the Laurales: Evidence from molecular and morphological data. Amer. J. Bot. 86:1301–1315.
Renner, S.S. & A.S. Chanderbali. 2000. What is the relationship among Hernandiaceae, Lauraceae, and Monimiaceae, and why is this question so difficult to answer? Int. J. Pl. Sci. 161:S109–S119.
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.
