Glandulocalyx upatoiensis, a fossil flower of Ericales (Actinidiaceae/ Clethraceae) from the Late Cretaceous (Santonian) of Georgia, USA

Jũrg Schõnenberger*, Maria Von Balthazar, Masamichi Takahashi, Xianghui Xiao, Peter R. Crane, Patrick S. Herendeen

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

32 Scopus citations

Abstract

Background and Aims Ericales are a major group of extant asterid angiosperms that are well represented in the Late Cretaceous fossil record, mainly by flowers, fruits and seeds. Exceptionally well preserved fossil flowers, here described as Glandulocalyx upatoiensis gen. sp. nov., from the Santonian of Georgia, USA, yield new detailed evidence of floral structure in one of these early members of Ericales and provide a secure basis for comparison with extant taxa. Methods The floral structure of several fossil specimens was studied by scanning electron microscopy (SEM), light microscopy of microtome thin sections and synchrotron-radiation X-ray tomographic microscopy (SRXTM). For direct comparisons with flowers of extant Ericales, selected floral features of Actinidiaceae and Clethraceae were studied with SEM. Key Results Flowers of G. upatoiensis have five sepals with quincuncial aestivation, five free petals with quincuncial aestivation, 2028 stamens arranged in a single series, extrorse anther orientation in the bud, ventral anther attachment and a tricarpellate, syncarpous ovary with three free styles and numerous small ovules on axile, protruding-diffuse and pendant placentae. The calyx is characterized by a conspicuous indumentum of large, densely arranged, multicellular and possibly glandular trichomes. Conclusions Comparison with extant taxa provides clear evidence for a relationship with core Ericales comprised of the extant families Actinidiaceae, Roridulaceae, Sarraceniaceae, Clethraceae, Cyrillaceae and Ericaceae. Within this group, the most marked similarities are with extant Actinidiaceae and, to a lesser degree, with Clethraceae. More detailed analyses of the relationships of Glandulocalyx and other Ericales from the Late Cretaceous will require an improved understanding of the morphological features that diagnose particular extant groups defined on the basis of molecular data.

Original languageEnglish (US)
Pages (from-to)921-936
Number of pages16
JournalAnnals of botany
Volume109
Issue number5
DOIs
StatePublished - Apr 2012

Keywords

  • Actinidiaceae
  • Clethraceae
  • Ericales
  • Glandulocalyx upatoiensis
  • Late Cretaceous
  • Santonian
  • flowers
  • fossils

ASJC Scopus subject areas

  • Plant Science

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