The Miocene genus Fupingopollenites: comparisons with ultrastructure and pseudocolpi in modern pollen

Abstract

The morphology of the geographically widespread (Asia and Europe) Miocene pollen genus Fupingopollenites Liu, is described from combined light, scanning and transmission electron microscopy. Comparisons are made with pollen of a number of living taxa, in orders Myrtales and Lamiales, as well as Boraginaceae, unplaced within Euasterids I. In these groups there are taxa with pollen bearing a superficial similarity in light microscopy, with respect to polar outline and pseudocolpi. Comparisons are also made with the genus Hoplestigmataceae, a family of uncertain position in recent analyses. The morphology of Fupingopollenites is discussed in relation both to the pollen of the extant taxa examined, and also to Tricolporopollenites wackersdorfensis Thiele-Pfeiffer (syn. Fupingopollenites), found in the presumed legume flowers of the lower to middle Miocene fossil Podocarpium podocarpum (A. Braun) Herendeen. The finely ridged exine and columellae of Fupingopollenites have not been described in the pollen of any living angiosperm species, although the fossil pollen does share one character found in the pollen of a number of legume taxa; a very thin, almost non-existent foot layer. The morphology of Fupingopollenites does not support a relationship near the Hoplestigmataceae as previously suggested. A possible palaeoecological environment for the parent plants of the Podocarpium flowers and of Tricoporopollenites ( Fupingopollenites) is also outlined. However, results do not resolve the hypothesis that the association between Tricoporopollenites ( Fupingopollenites) and P. podocarpium flowers is a natural one, and most probably legume in origin. Whatever their origin, the fossil pollen grains seem to represent a highly successful but extinct late Tertiary taxon whose relationships remain uncertain. The possible relationships of Hoplestigmataceae are discussed, and it is concluded that, based on pollen data, the family may be near Boraginaceae.