Ultrastructural studies of some fossil and extant palm pollen, and the reconstruction of the biogeographical history of subtribes Iguanurinae and Calaminae
Abstract
Two monosulcate and one disulcate palm-like pollen types are described from a Middle Eocene lignite sample at Watupuru River, near Kalisonggo, Nanggulan, Central Java. Their morphologies are described by light, scanning electron and transmission electron microscopy. Systematically arranged, morphological data of recent palm pollen are used as a broad base for comparisons with the fossil grains. Affinities of the fossil grains within the Palmae are considered, both in a systematic context, and in the light of their palaeo- and recent geography, climate and ecology. The two monosulcate forms are compared to the fossil form-genus Palmaepollenites. One form is compared to P. kutchensis which has a well-defined Eocene plant-geographical province, spanning the Indian plate and the Southeast Asian region west of Wallace's Line. Palmaepollenites kutchensis most closely compares to genera exhibiting relict distributions, emphasising an ancient lineage. The closest matches are confined to Pacific island (Pritchardia, Lepidorrachis) or to New Caledonia genera (Basselinia, Burretiokentia). Morphological, ecological and plant geographical data suggest a probable affinity with the subtribe Iguanurinae of the tribe Areceae. The source taxon of Palmaepollenites kutchensis probably evolved on the Indian plate in the Paleocene, or possibly the Late Cretaceous, and migrated into Southeast Asia following collision with Asia in the Middle Eocene. Due to drier climates in the Oligocene it became sparse in the Indonesian region, and subsequently became extinct.
The third pollen type is referred to Dicolpopollis malesianus. It closely compares with pollen of some species in the genera Calamus and Ceratolobus of subtribe Calaminae: Calamoideae.- Publication:
-
Review of Palaeobotany and Palynology
- Pub Date:
- 1995
- DOI:
- 10.1016/0034-6667(94)00133-5
- Bibcode:
- 1995RPaPa..85..153H