title: Glandulocalyx upatoiensis, a fossil flower of Ericales (Actinidiaceae/Clethraceae) from the Late Cretaceous (Santonian) of Georgia, USA.
abstract: OBJECTIVE
  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.
  
  
  RESULTS
  Flowers of G. upatoiensis have five sepals with quincuncial aestivation, five free petals with quincuncial aestivation, 20-28 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.
authors.affiliation: Department for Structural and Functional Botany, Faculty Centre of Biodiversity, University of Vienna, Rennweg 14, Vienna, Austria. juerg.schoenenberger@univie.ac.at
authors.forename: Jürg
authors.initials: J
authors.lastname: Schönenberger
authors.forename: Maria
authors.initials: M
authors.lastname: von Balthazar
authors.forename: Masamichi
authors.initials: M
authors.lastname: Takahashi
authors.forename: Xianghui
authors.initials: X
authors.lastname: Xiao
authors.forename: Peter R
authors.initials: PR
authors.lastname: Crane
authors.forename: Patrick S
authors.initials: PS
authors.lastname: Herendeen
mesh_terms: D029041:Actinidiaceae / Q000033:anatomy & histology* / Q000235:genetics; D005075:Biological Evolution; D031250:Clethraceae / Q000033:anatomy & histology* / Q000235:genetics; D035264:Flowers / Q000033:anatomy & histology* / Q000235:genetics / Q000648:ultrastructure; D005580:Fossils; D005638:Fruit / Q000033:anatomy & histology / Q000235:genetics; D005845:Georgia; D019684:Magnoliopsida / Q000033:anatomy & histology* / Q000235:genetics; D008855:Microscopy, Electron, Scanning; D010802:Phylogeny; D012639:Seeds / Q000033:anatomy & histology / Q000235:genetics