Thorezia vezerensisgen. et sp. nov., a new seed plant with multiovulate cupules from the Late Devonian of Belgium

Abstract

The multiovulate cupule of a new spermatophyte, Thorezia vezerensisgen. et sp. nov., is described from the Late Devonian aged sediments from Trooz Quarry in Belgium. In gross morphology, it conforms to the Moresnetia morphotype and has a cupule that is composed of four independent quarters that each dichotomises three times. Each cupule quarter contains one single ovoid preovule with a long pedicel and an integument that has small apical teeth surrounding a rudimentary micropyle. Morphological variability in the materials examined is interpreted as being related to preovule maturity, and from this a good understanding of the ontogenetic development from preceding dispersal has been developed. Up to now, 17 spermatophyte species have been described, 11 of which come from eastern Laurussia. This diversity in eastern Laurussia contrasts strongly with the low diversity characterizing contemporaneous floras from other phytogeographical areas. We suggest here that the arid climatic conditions prevailing in eastern Laurussia favoured the development of diverse spermatophyte communities and contributed to reduced diversity and abundance of contemporaneous free-sporing plant diversity.

Keywords::

• Cupule
• Evieux flora
• fossil plant
• integument
• preovule
• Upper Devonian

Acknowledgements

We thank M. Gaipl for having collected this material and giving it to the ULg. We also thank Dr M. Fairon-Demaret for her useful comments and support that would have justified her being co-author of this publication. We also thank Jonica Dos Remedios for helping illustrating the paper.