Multiporate Poaceae pollen grains observed in the recent fossil record from the Greater Serengeti Ecosystem and Lake Victoria region

The analysis of fossil pollen from sediments is used to understand past vegetation and land cover variability. The observations of multiporate Poaceae pollen from sediments have received little attention in the literature and causes and rates of occurrence have few estimates, and the rates observed in the sediments are much lower than estimates observed from modern plants in Asia. Pollen analysis of the uppermost sediments from Speke Gulf, Lake Victoria, eastern Africa, showed relative abundances of Poaceae between 65 and 75% during the past centuries. A total of 19 of the ∼ 11,000 Poaceae pollen grains observed had conspicuous morphological variations and were documented. More consistent presence of abnormal grains occurred since the mid twentieth century, at the same time of increased anthropogenic environmental stressors. Multiporate pollen grains of Poaceae have been previously observed in Asia, South America, and northern Africa, predominantly in the Panicoideae subfamily. Morphological variations may present an added challenge for automated pollen identification techniques and descriptions of fossil pollen. • Pore apertures on Poaceae pollen grains may exhibit morphological variability. • Diporate and triporate Poaceae grains were observed in the last two centuries of recent Lake Victoria sediments. • A combination of environmental stressors may influence the development of pollen abnormalities. • Variability of pollen morphology in the fossil record may be an indicator of paleoecological-stress responses.