Palynology of Middle Tertiary lacustrine deposits

Palynology of Middle Tertiary lacustrine deposits 253
metrical and parallel arrangement. Exine two-layered, laevigate or chagrenate, I­
1. 5 pm thick; ectexine as thick as endexine. Germinal pores round or slightly
lalongated.
Measurements: 30-33 pm in length.
. 23 - 25 pm in width.
Width / length ratio: 0.75-0.8.
Previous record: Burundi (Africa): Late Neogene (Rusizi valley).
Remarks: The specimens refer to Sapotaceoidaepollenites africanus Sah and have to be
combined with the genus Tetracolporopollenites Pflug & Thomson 1953.
Botanical affinity: Sapotaceae.
Genus Polybrevicolporites Venkatachala & Kar 1969.
Type species: Polybrevicolporites cephalus Venkatachala & Kar 1969.
Polybrevicolporites sp.
PI. 5, figs. 6 a-c.
Description: Polycolporate pollen grain. Figura subcircular in oblique view. Five
relatively short colpi converging at the apices. Pores well developed, large, round,
3.5 pm in diameter. Exine 4.5 pm thick, chagrenate.
Measurements: 35.5 pm in diameter.
Remarks: Only one specimen was observed.
Botanical affinity: Unknown.
Genus Polygalacidites Sah & Dutta 1966.
Type species: Polygalacidites clarus Sah & Dutta 1966.
Polygalacidites sp.
PI. 5, figs. 5 a - b.
Description: Polycolporate (ten-colporate) pollen of almost globular shape. Ten long
colpi, extending in radial symmetry to the poles. Ora (pores) equidistantly placed in
an equatorial belt (synorate). Exine chagrenate. Mesocolpia 4 -5.5 pm wide.
Measurements: 31 X 34 pm in diameter.
Remarks: The single specimen encountered contrasts with Polygalacidites clarus Sah
& Dutta (1966) from Assam and P. speciosus Takahashi (1982) from lava in both
the number of colpi and the synora.
Botanical affinity: Polygalaceae, Polygala.