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Fossil pollen believed to be related to extant Hagenia abyssinica were discovered in the early Miocene (21.73 Ma) Mush Valley paleoflora, Ethiopia, Africa. Both the fossil and extant pollen grains of H. abyssinica were examined with combined light microscopy, scanning electron microscopy, and transmission electron microscopy to compare the pollen and establish their relationships. Based on this, the fossil pollen grains were attributed to Hagenia. The presence of Hagenia in the fossil assemblage raises the questions if its habitat has changed over time, and if the plants are/were wind pollinated. To shed light on these questions, the morphology of extant anthers was also studied, revealing specialized hairs inside the anthers, believed to aid in insect pollination. Pollen and anther morphology are discussed in relation to the age and origin of the genus within a molecular dated phylogenetic framework, the establishment of complex topography in East Africa, other evidence regarding pollination modes, and the palynological record. The evidence presented herein, and compiled from the literature, suggests that Hagenia was an insect‐pollinated lowland rainforest element during the early Miocene of the Mush Valley. The current Afromontane habitat and ambophilous (insect and wind) pollination must have evolved in post‐mid‐Miocene times. [ABSTRACT FROM AUTHOR]

The continued investigation of the middle Miocene palynoflora from the Lavanttal Basin reveals numerous additional angiosperm taxa. The Myrtales to Ericales pollen record documented here comprises 46 different taxa belonging to Onagraceae (Ludwigia), Ericaceae (Craigia, Reevesia, Tilia), Anacardiaceae (Pistacia), Rutaceae (Zanthoxylum), Sapindaceae (Acer), Santalaceae (Arceuthobium), Amaranthaceae, Caryophyllaceae, Polygonaceae (Persicaria, Rumex), Cornaceae (Alangium, Cornus, Nyssa), Ebenaceae (Diospyros), Ericaceae (Andromeda, Arbutus, Empetrum, Erica), Sapotaceae (Pouteria, Sideroxylon), Styracaceae (Rehderodendron) and Symplocaceae (Symplocos). Köppen signatures of potential modern analogues of the additional fossil woody elements confirm the hypothesis of a subtropical (Cfa, Cwa) climate at lower elevations and subsequent transition into a temperate climate with altitudinal succession (Cfa → Cfb/Dfa → Dfb; Cwa → Cwb → Dwb-climate). The fossil plants represent different vegetation units, from wetland lowlands to well-drained montane forests. Many of the fossil taxa have potential modern analogues that can be classified as nemoral and/or meridio-nemoral and/or semihumid-meridional vegetation elements. New is the recognition of oreotropical elements, which are direct indicators for a substantial altitudinal gradient. [ABSTRACT FROM AUTHOR]

The palm family, Arecaceae, is notoriously depauperate in Africa today, and its evolutionary, paleobiogeographic, and extinction history there are not well documented by fossils. In this article we report the pollen of two new extinct species of the small genus, Sclerosperma (Arecoideae), from a late Oligocene (27-28 Ma) stratum exposed along the Guang River in Chilga Wereda of north-western Ethiopia. The pollen are triporate, and the two taxa can be distinguished from each other and from modern species using a combination of light and scanning electron microscopy, which reveals variations in the finer details of their reticulate to perforate exine sculpture. We also report a palm leaf fragment from a stratum higher in the same section that is in the Arecoideae subfamily, and most likely belongs to Sclerosperma. The implications of these discoveries for the evolutionary history of this clade of African arecoid palms is that their diversification was well underway by the middle to late Oligocene, and they were much more widespread in Africa at that time than they are now, limited to West and Central Africa. Sclerosperma exhibits ecological conservatism, as today it occurs primarily in swamps and flooded forests, and the sedimentology of the Guang River deposits at Chilga indicate a heterogeneous landscape with a high water table. The matrix containing the fossil pollen is lignite, which itself indicates standing water, and a variety of plant macrofossils from higher in the section have been interpreted as representing moist tropical forest or seasonally inundated forest communities. [ABSTRACT FROM AUTHOR]

Three currently accepted Sclerosperma species appear to produce four different pollen morphologies. Sclerosperma mannii and S. walkeri pollen share the same distinct reticulate sculpture, but S. profizianum produces three different pollen types (microreticulate, fossulate, and perforate). The pollen morphology suggests that S. mannii and S. walkeri are sister taxa of the same intrageneric lineage. The pollen diversity observed in S. profizianum suggests (a) this taxon is unique regarding its pollen diversity despite being a non-heterostylous plant or (b) that circumscription of S. profizianum as a species may well be in the need of redefinition. [ABSTRACT FROM AUTHOR]

An ongoing re-investigation of the early Miocene Saldanha Bay (South Africa) palynoflora, using combined light and scanning electron microscopy (single grain method), is revealing several pollen types new to the African fossil record. One of the elements identified is Loranthaceae pollen. These grains represent the first and only fossil record of Loranthaceae in Africa. The fossil pollen grains resemble those produced by the core Lorantheae and are comparable to recent Asian as well as some African taxa/lineages. Molecular and fossil signals indicate that Loranthaceae dispersed into Africa via Asia sometime during the Eocene. The present host range of African Loranthaceae and the composition of the palynoflora suggest that the fossil had a range of potential host taxa to parasitise during the early Miocene in the Saldanha Bay region. [ABSTRACT FROM AUTHOR]

When applying high-resolution microscopy, the pollen morphology of extant taxa can be used to classify fossil pollen, that is, to address the latter in the established systematic-phylogenetic framework. Here we investigate tetrads and pollen features of 20 different Winteraceae species, most of them belonging to the early-diverging generic lineages Tasmannia, Drimys and Pseudowintera. The tetrads and pollen are grouped into eleven pollen types based on diagnostic features observed by both light and scanning electron microscopy. The high-resolution scanning electron micrographs of recent material allow detailed comparison with fossil material, resulting in a more accurate affiliation of fossil tetrads/pollen to extant lineages. As a case study, early Miocene Winteraceae tetrads from South Africa are re-examined and formally described. The systematic placement of the African fossils is discussed in light of the pollen types presented here. [ABSTRACT FROM AUTHOR]

The pantropical Picrodendraceae produce mostly spheroidal to slightly oblate, echinate pollen grains equipped with narrow circular to elliptic pori that can be hard to identify to family level in both extant and fossil material using light microscopy only. Fossil pollen of the family have been described from the Paleogene of America, Antarctica, Australia, New Zealand, and Europe, but until now none have been reported from Afro-India. Extant pollen described here include representatives from all recent Picrodendraceae genera naturally occurring in Africa and/or Madagascar and south India and selected closely related tropical American taxa. Our analyses, using combined light microscopy and scanning electron microscopy, show that pollen of the Afro-Indian genera encompass three morphological types: Type 1, comprising only Hyaenanche ; Type 2, including Aristogeitonia , Mischodon, Oldfieldia and Voatamalo ; Type 3, comprising the remaining two genera, Androstachys and Stachyandra . Based on the pollen morphology presented here it is evident that some previous light microscopic accounts of spherical and echinate fossil pollen affiliated with Arecaceae, Asteraceae, Malvaceae, and Myristicaceae from the African continent could belong to Picrodendraceae. The pollen morphology of Picrodendraceae, fossil pollen records, a dated intra-familial phylogeny, seed dispersal modes, and the regional Late Cretaceous to early Cenozoic paleogeography, together suggest the family originated in the Americas and dispersed from southern America across Antarctica and into Australasia. A second dispersal route is believed to have occurred from the Americas into continental Africa via the North Atlantic Land Bridge and Europe.

Three currently accepted Sclerosperma species appear to produce four different pollen morphologies. Sclerosperma mannii and S. walkeri pollen share the same distinct reticulate sculpture, but S. profizianum produces three different pollen types (microreticulate, fossulate, and perforate). The pollen morphology suggests that S. mannii and S. walkeri are sister taxa of the same intrageneric lineage. The pollen diversity observed in S. profizianum suggests (a) this taxon is unique regarding its pollen diversity despite being a non-heterostylous plant or (b) that circumscription of S . profizianum as a species may well be in the need of redefinition.

The palm family, Arecaceae, is notoriously depauperate in Africa today, and its evolutionary, paleobiogeographic, and extinction history there are not well documented by fossils. In this article we report the pollen of two new extinct species of the small genus, Sclerosperma (Arecoideae), from a late Oligocene (27-28 Ma) stratum exposed along the Guang River in Chilga Wereda of north-western Ethiopia. The pollen are triporate, and the two taxa can be distinguished from each other and from modern species using a combination of light and scanning electron microscopy, which reveals variations in the finer details of their reticulate to perforate exine sculpture. We also report a palm leaf fragment from a stratum higher in the same section that is in the Arecoideae subfamily, and most likely belongs to Sclerosperma . The implications of these discoveries for the evolutionary history of this clade of African arecoid palms is that their diversification was well underway by the middle to late Oligocene, and they were much more widespread in Africa at that time than they are now, limited to West and Central Africa. Sclerosperma exhibits ecological conservatism, as today it occurs primarily in swamps and flooded forests, and the sedimentology of the Guang River deposits at Chilga indicate a heterogeneous landscape with a high water table. The matrix containing the fossil pollen is lignite, which itself indicates standing water, and a variety of plant macrofossils from higher in the section have been interpreted as representing moist tropical forest or seasonally inundated forest communities.