Scanning electron microscopy investigations of middle to late Eocene pollen from the Changchang Basin (Hainan Island, South China) - In-sights into the paleobiogeography and fossil history of Juglans, Fagus, Lagerstroemia, Mortoniodendron, Cornus, Nyssa, Symplocos and some Icacinaceae in SE Asia

• Published in: Review of Palaeobotany and Palynology
• Main Authors: Hofmann, Christa-Ch., Kodrul, Tatiana M., Liu, Xiaoyan, Jin, Jianhua
• Format: Report
• Language: English
• Published: ELSEVIER SCIENCE BV 2019
• Subjects: Middle-late Eocene pollen; SEM investigation; Paleobiogeography; PHYLLANTHUS SPECIES EUPHORBIACEAE; PALMS SHEDS LIGHT; NORTH-AMERICA; SP-NOV; SHOREA DIPTEROCARPACEAE; GLOBAL BIOGEOGRAPHY; WINGED FRUITS; 1ST RECORD; MORPHOLOGY; CLASSIFICATION; Plant Sciences; Paleontology; Canada; Greenland
• Online Access: http://ir.nigpas.ac.cn/handle/332004/22319; http://ir.nigpas.ac.cn/handle/332004/22320; https://doi.org/10.1016/j.revpalbo.2019.02.004

Bartonian-aged samples from the Changchang Formation (Hainan) have been palynologically analyzed using light microscopy (LM) and scanning electron microscopy (SEM). The presence of cf. Laurelia-type pollen demonstrates a wide geographical range for this family during the Eocene. A particular paleobiogeographic pattern, suggesting Eurasia as the place of origin, can be seen from six pollen taxa: (1) A Flueggea-type, together with previously found European Flueggea fossils, (2) a Nyssa-type closely resembling the extant Nyssa sinensis and upper Eocene Nyssa pollen from Europe, (3) three Symplocos-types, which are closely related to the early diverging Symplocos subgenus Palura, resemble upper Eocene Symplocos pollen from Germany, and (4) a Cornus-type belonging to the "blue-or-white-fruited Glade," like several Corn us fossils from Europe. In contrast, an Asian paleobiogeographic pattern can be seen from six Hainan taxa: (1) Two Phyllanthus subgen. Eriococcus/Isocladus-types, here described for the first time, that, so far, occur only in China, (2) a Lagerstroemia-type that resembles pollen of the Miocene Lagerstroemia cathayensis from China and pollen of two extant deciduous Lagerstroemia taxa, (3) a Juglans-type that is assumed to belong to Juglans section Cardiocaryon, and (4) two Dipterocarpaceae pollen types (cf. Dipterocarpus and cf. Diyobalanops) that are here described for the first time from Eocene strata outside India. A much wider distribution can be observed with the Fagus-type pollen closely resembling pollen of the extant Fagus "subgenus Engleriana" and Paleogene Fagus pollen from Greenland and Canada, suggesting an amphipacific distribution of an ancient Fagus "Engleriana lineage" during the Eocene. The Craigia-type corroborates the presence of Craigia diaspores from the Changchang Formation and two Mortoniodendron-types reveal a particular paleobiogeographical history; extant Mortoniodendron grows in Central America and is known there since the Miocene. However, Eocene Mortoniodendron-type pollen from Europe and now Hainan indicate a far wider distribution of this genus. The two lodes types, one resembling African/Madagascar taxa and one a Melanesian taxon, suggest that the Old World disjunction of lodes in Africa/Madagascar and SE Asia is a Paleogene relict, whereas the third Icacinaceae taxon resembles two genera of the Mappia/Nothapodytes Glade, where Mappia occurs today in Central America and Nothapodytes in SE Asia. (C) 2019 Elsevier B.V. All rights reserved.