Origin and Early Evolution of Hydrocharitaceae and the Ancestral Role of <i>Stratiotes</i>
Silvia Ulrich,
Manuel Vieira,
Mario Coiro,
Johannes M. Bouchal,
Christian Geier,
Bonnie F. Jacobs,
Ellen D. Currano,
Olaf K. Lenz,
Volker Wilde,
Reinhard Zetter,
Friðgeir Grímsson
Affiliations
Silvia Ulrich
Department of Botany and Biodiversity Research, University of Vienna, 1030 Vienna, Austria
Manuel Vieira
Department of Earth Sciences, GeoBioTec, NOVA School of Science and Technology, Campus de Caparica, 2829-516 Caparica, Portugal
Mario Coiro
Department of Palaeontology, University of Vienna, 1090 Vienna, Austria
Johannes M. Bouchal
Department of Botany and Biodiversity Research, University of Vienna, 1030 Vienna, Austria
Christian Geier
Department of Botany and Biodiversity Research, University of Vienna, 1030 Vienna, Austria
Bonnie F. Jacobs
Roy M. Huffington Department of Earth Sciences, Southern Methodist University, Dallas, TX 75275, USA
Ellen D. Currano
Departments of Botany and Geology & Geophysics, University of Wyoming, Laramie, WY 82071, USA
Olaf K. Lenz
Institute of Applied Geosciences, Technical University Darmstadt, 64287 Darmstadt, Germany
Volker Wilde
Section Palaeobotany, Division Palaeontology and Historical Geology, Senckenberg Research Institute and Natural History Museum Frankfurt, 60325 Frankfurt am Main, Germany
Reinhard Zetter
Department of Botany and Biodiversity Research, University of Vienna, 1030 Vienna, Austria
Friðgeir Grímsson
Department of Botany and Biodiversity Research, University of Vienna, 1030 Vienna, Austria
The combined morphological features of Stratiotes (Hydrocharitaceae) pollen, observed with light and electron microscopy, make it unique among all angiosperm pollen types and easy to identify. Unfortunately, the plant is (and most likely was) insect-pollinated and produces relatively few pollen grains per flower, contributing to its apparent absence in the paleopalynological record. Here, we present fossil Stratiotes pollen from the Eocene of Germany (Europe) and Kenya (Africa), representing the first reliable pre-Pleistocene pollen records of this genus worldwide and the only fossils of this family discovered so far in Africa. The fossil Stratiotes pollen grains are described and compared to pollen from a single modern species, Stratiotes aloides L. The paleophytogeographic significance and paleoecological aspects of these findings are discussed in relation to the Hydrocharitaceae fossil records and molecular phylogeny, as well as the present-day distribution patterns of its modern genera.
