2026/07/15 by Christa-Ch. Hofmann, Silvia Ulrich, Mario Coiro +2 · 1 voice
Agricultural and Biological Sciences · Earth and Planetary Sciences · #Fossil Insects in Amber #Paleontology and Stratigraphy of Fossils #Plant Diversity and Evolution
paper · pdf · doi:10.3897/fr.29.196612
openalex publication_date 2026/07/15 · openalex created_date 2026/07/16 · openalex updated_date 2026/07/20
Aquifoliales are an early diverging clade of asterids and its important, large woody genus Ilex is widespread in moist, warm to tropical habitats today. The origin and evolution of Ilex are still under debate because fossils assigned to Ilex often are seen as ambiguous and their fossil occurrence predates inferred molecular ages of the Ilex crown group. LM, SEM and TEM analyses of tricolpate and tricryptoaperturate Gemmatricolpites pollen from the Aptian Rio da Batateira Formation (Brazil) reveal an atectate, clavate to baculate ektexine with microrugulate suprasculpture. Gemmatricolpites has a thicker ektexine and similarly structured wall layers, but different aperture types compared to extant Ilex (tricolporate). Several ‘ Ilex -like pollen’ from Europe and South China (early Eocene to Middle Miocene) are double in size and display similar ektexine sculpture and ornamentation, but are tricolpate or tricolporate. Today, some plant genera do show variable pollen apertural conditions, so these variable apertures through time may not result solely from convergence. Gemmatricolpites grains from the late Early Cretaceous palaeotropics may then, in fact, represent an extinct lineage of Aquifoliales because their ektexine strongly resembles that of extant Ilex pollen, despite the apertural difference, whilst the double size can be interpreted as the result of whole genome duplication. After reviewing reported Gemmatricolpites occurrences and nearly cosmopolitan occurrence of tricolpate Ilexpollenites pollen and Ilex seeds from Upper Cretaceous strata, we suggest this would witness the origin of an ancient, now extinct lineage of Aquifoliales in North Gondwana, and its evolution and lateral migration during the Cretaceous.