Programinis burmitis gen. et sp. nov., and P. laminatus sp. nov., Early Cretaceous grass-like monocots in Burmese amber

Abstract

The remains of a spikelet and a leaf of an Early Cretaceous grass-like monocot in Burmese amber are described as Programinis burmitis gen. et sp. nov., and P. laminatus sp. nov., respectively. The laterally compressed spikelet of P. burmitis has two basal sterile glumes, a series of lemmas and paleas and remains of stamens and a gynoecium. Adjacent to the spikelet are spherical, monoporate pollen grains. The epidermis of the leaf fragment of P. laminatus contains numerous stomata with well-defined, sausage-shaped guard cells with elongate nuclei, rows of epidermal cells with long and short cells and spherical and elliptical silica-like bodies in cuboid epidermal cells. Unpointed papillae and uniseriate bicellular microhairs, both raised, occur on the leaf surface. Programinis burmitis and P. laminatus are considered early bambusoid types that grew in tropical, forested habitats. Their discovery suggests that true grasses may have evolved in South-east Asia, since the Burmese amber mines are located on the Burma Plate, part of Laurasia.