中国科学院南京地质古生物研究所机构知识库

As a crossroads for plant dispersal between Laurasia and Gondwana since at least the late Eocene, the Central Myanmar Basins have yielded rich and diverse fossil pollen. Here we report Grimmipollis burmanica, a new genus and species in the soapberry family (Sapindaceae) from the upper Eocene Yaw Formation in the Central Myanmar Basins. We also investigate its similarity of pollen sculpture with other selected genera using hierarchi-cal cluster analysis, and its source paleoecology with pollen diagrams. Grimmipollis pollen grains are character-ized by parasyncolporate apertures with an apocolpial field at each side, distinct margines along the colpi, arcuate, tuberculate and rope-shaped mesocolpial ridges, and prominent, verrucate or fossulate apocolpia. These features distinguish this genus from other syncolporate and parasyncolporate types in the extant Sapindaceae genera, and fossil pollen genera. As most syncolporate and parasyncolporate types occur in the tribe Cupanieae, G. burmanica is likely derived from an extinct Cupanieae and thus a rainforest tree species. The hierarchical cluster analysis confirms our establishment of Grimmipollis, and reveals it is morphologically close to Meyeripollis. The sedimentary environment from which these pollen grains were retrieved suggests that G. burmanica could be a member of seasonal swamp forests.(c) 2022 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http:// creativecommons.org/licenses/by-nc-nd/4.0/).