Triporate pollen in the Arecaceae

Valkenburg

Wieringa

et al. 2018

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.

Section: Descriptive Palynologymentioning

confidence: 99%

Section: Descriptive Palynologymentioning

confidence: 99%

mentioning

confidence: 99%

See 1 more Smart Citation

Pollen morphology of the African Sclerosperma (Arecaceae)

Valkenburg

Wieringa

et al. 2018

“…The unique pollen morphology of Sclerosperma (triangular, triporate, reticulate) within the Arecaceae was first noted by Erdtman and Sing (1957) and often discussed by M.M. Harley and collaborators in the years 1991 to 2008 during their comprehensive work on the pollen morphology of this family (Harley & Hall 1991;Harley 1996Harley , 1999Harley , 2004Harley & Baker 2001;Harley & Dransfield 2003;Dransfield et al 2008).…”

mentioning

confidence: 99%

Sclerospermafossils from the late Oligocene of Chilga, north-western Ethiopia

Jacobs

Valkenburg

et al. 2018

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 northwestern 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.

“…Staining using KMnO 4 ( Figure 4E) clearly differentiates the layers of the exine compared to conventional staining ( Figure 4F). In this case it seems more likely that the thick basal layer is actually a thin compact-continuous foot layer accompanied by a thick continuous-compact endexine ( Figure 4E) (see also Harley & Dransfield 2003). Still, as pollen/spore taxa may react differently to chemical treatment, the use of diverse preparation and staining methods is always recommended.…”

mentioning

confidence: 99%

The single-grain method: adding TEM to the equation

Ulrich

2019

An advanced protocol to prepare single extant and fossil pollen grains for transmission electron microscopy (TEM) analysis allows for the fast recovery of data on the ultrastructure of pollen/spores. The protocol is easy to apply and less time consuming than previous methods. The 'loss' of pollen grains and pollen that is 'difficult to locate' within the embedding material is avoided, and each single pollen grain can be prepared successfully for TEM analysis. This preparation method is meant as an addition to the single-grain method using combined light and scanning electron microscopy to investigate dispersed fossil pollen grains developed by Dr Reinhard Zetter in the late 1980s.