More diverse and abundant than assumed: Eucommiidites pollen preserved in a deltaic setting (Lower Cretaceous) of the Araripe Basin (NE Brazil)

Twelve species of Eucommiidites pollen from deltaic sedimentary rocks of the Rio da Batateira and lowermost Crato formations are here described and depicted with light microscopy (LM) and scanning electron microscopy (SEM). A clump of Eucommiidites sp. 6 from sample CAS 27 of the lowermost Crato Formation is thought to be the dispersed equivalent of in situ pollen of Araripestrobus resiniferous found in the laminitic limestone of the Crato Formation. The other Eucommiidites taxa are known only as dispersed taxa. The separation of individual Eucommiidites species using LM is often very difficult and helped by the use of SEM to observe the position of lateral sulci/furrows, plus the sculpture and ornamentation of the sulcus membrane and ektexine. Only two Eucommidiites taxa , E . sp. 2 and E . sp. 3, occur frequently and generally abundantly in medium percentages (4 to 15%) in the pollen sum throughout the section, and are interpreted to come from either wind pollinated plants or plants with no specific edaphic requirements. All other taxa are interpreted to have grown further away from the distributary channels, probably in more specialized stands. Two of them ( Eucommiidites sp. 6 and E . sp. 8) are preserved in clumps and are suggested to be animal pollinated. The presence of unusually high percentages of 8 to 14 % of Eucommiidites in the pollen sums reveal that Eucommiidites taxa constituted a significant portion of the ancient vegetation habitats located upriver, but only comprise a few fragments in the macrofossil record of the Araripe Basin. • The studied Aptian succession is in the Araripe Basin, Brazil. • The pollen taxon Eucommiidtes was far more abundant and diverse than expected. • All together, 12 taxa were recognised, and with very high abundances (up to 14 %). • Eucommiidites was more common in the vegetation than previously assumed.