Origin and divergence of Afro-Indian Picrodendraceae: linking pollen morphology, dispersal modes, fossil records, molecular dating and paleogeography

Author(s)
Fridgeir Grimsson, Shirley A. Graham, Mario Coiro, Bonnie F. Jacobs, Alexandros Xafis, Frank H. Neumann, Louis Scott, Jakub Sakala, Ellen D. Currano, Reinhard Zetter
Abstract

The pantropical Picrodendraceae produce mostly spheroidal to slightly oblate, echinate pollen grains equipped with narrow circular to elliptic pori that can be hard to identify to family level in both extant and fossil material using light microscopy only. Fossil pollen of the family have been described from the Paleogene of America, Antarctica, Australia, New Zealand, and Europe, but until now none have been reported from Afro-India. Extant pollen described here include representatives from all recent Picrodendraceae genera naturally occurring in Africa and/or Madagascar and south India and selected closely related tropical American taxa. Our analyses, using combined light microscopy and scanning electron microscopy, show that pollen of the Afro-Indian genera encompass three morphological types: Type 1, comprising only Hyaenanche; Type 2, including Aristogeitonia, Mischodon, Oldfieldia and Voatamalo; Type 3, comprising the remaining two genera, Androstachys and Stachyandra. Based on the pollen morphology presented here it is evident that some previous light microscopic accounts of spherical and echinate fossil pollen affiliated with Arecaceae, Asteraceae, Malvaceae, and Myristicaceae from the African continent could belong to Picrodendraceae. The pollen morphology of Picrodendraceae, fossil pollen records, a dated intra-familial phylogeny, seed dispersal modes, and the regional Late Cretaceous to early Cenozoic paleogeography, together suggest the family originated in the Americas and dispersed from southern America across Antarctica and into Australasia. A second dispersal route is believed to have occurred from the Americas into continental Africa via the North Atlantic Land Bridge and Europe.

Organisation(s)
Department of Botany and Biodiversity Research, Department of Palaeontology
External organisation(s)
Missouri Botanical Garden, Universität Zürich (UZH), Southern Methodist University, University of Witwatersrand, University of the Free State, Charles University Prague, University of Wyoming
Journal
Grana
Volume
58
Pages
227-275
No. of pages
49
ISSN
0017-3134
DOI
https://doi.org/10.1080/00173134.2019.1594357
Publication date
07-2019
Peer reviewed
Yes
Austrian Fields of Science 2012
105112 Historical geology, 105117 Palaeobotany, 106008 Botany, 106029 Plant morphology
Keywords
ASJC Scopus subject areas
Earth and Planetary Sciences(all)
Portal url
https://ucris.univie.ac.at/portal/en/publications/origin-and-divergence-of-afroindian-picrodendraceae-linking-pollen-morphology-dispersal-modes-fossil-records-molecular-dating-and-paleogeography(722f536b-9803-4246-8cad-25016f38a455).html