Grimmipollis burmanica gen. et sp. nov.: New genus of the soapberry family (Sapindaceae) from the late Eocene of central Myanmar

Huasheng Huang (1, 2) , Robert J Morley (3) , Raymond van der Ham (4) , Limi Mao (5) , Alexis Licht (6) , Guillaume Dupont-Nivet (7, 8) , Zaw Win (9) , Day Wa Aung (10) , Carina Hoorn (1)

1 UvA - University of Amsterdam [Amsterdam] = Universiteit van Amsterdam
2 UniFI - Università degli Studi di Firenze = University of Florence = Université de Florence
3 University of London [London]
4 Naturalis Biodiversity Center [Leiden]
5 NIGPAS-CAS - Nanjing Institute of Geology and Palaeontology
6 CEREGE - Centre européen de recherche et d'enseignement des géosciences de l'environnement
7 GR - Géosciences Rennes
8 University of Potsdam = Universität Potsdam
9 Shwe Bo University
10 University of Yangon

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 hierarchical cluster analysis, and its source paleoecology with pollen diagrams. Grimmipollis pollen grains are characterized 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.

Domaines: Paléontologie

Huasheng Huang, Robert J Morley, Raymond van der Ham, Limi Mao, Alexis Licht, et al.. Grimmipollis burmanica gen. et sp. nov.: New genus of the soapberry family (Sapindaceae) from the late Eocene of central Myanmar. Review of Palaeobotany and Palynology, 2023, 309, pp.104818. ⟨10.1016/j.revpalbo.2022.104818⟩. ⟨insu-03897654⟩