Sinolobotheca gen. nov., a Late Devonian ovule without cupule and its implication for integument functions

Area of Science:

• Paleobotany
• Evolutionary Biology
• Plant Morphology

Background:

• Earliest seed plant ovules from the Late Devonian (Famennian) are often detached and possess cupules.
• The precise functions of these early ovules remain under-researched.

Purpose of the Study:

• To investigate the morphology and evolutionary significance of early seed plant ovules.
• To describe a new taxon of Famennian ovule and infer its ecological functions.

Main Methods:

• Fossil plant collection during fieldwork.
• Specimen preparation using steel needles.
• Microscopic examination of numerous transverse sections of ovules.

Main Results:

• A new genus and species, Sinolobotheca octa gen. et sp. nov., was identified from the Famennian of China.
• Sinolobotheca ovules lack cupules, terminate dichotomous branches, and feature eight unique, proximally fused, distally converging, laterally separate integumentary lobes.
• These lobes are elongate, flat, curve outwards, and contain abundant thin-walled cells, largely free from the nucellus.

Conclusions:

• The discovery of Sinolobotheca supports the hypothesis that cupules were potentially lost in some Famennian ovules.
• Increased complexity and importance of integuments, including flattening and parenchyma, suggest evolved functions in photosynthesis and nutrient/water storage.
• The absence of a differentiated nucellar tip in Sinolobotheca may indicate that it did not rely on hydrasperman reproduction characteristic of early seed plants.