A voltzialean pollen cone from the Triassic of Antarctica

Leastrobus fallae gen. et sp. nov. is a morphotaxon representing structurally preserved microsporangiate strobili with in situ pollen from the Triassic of Antarctica. The small cone consists of a central axis with a region of helically arranged microsporophylls subtended by elongate, bilaterally symmetrical bracts. Each microsporophyll is differentiated into a pedicel and a laminar head; numerous (ca. 7) elongate microsporangia are attached to the inner surface of the laminar head. Pollen is protosaccate with two large sacci, a corpus with reticulate ornamentation, and a well-defined distal aperture. Leastrobus represents the first documented microsporangiate conifer cone and the first evidence of “Voltziales” from the permineralized floras of the Triassic of Antarctica. The combination of polysporangiate microsporophylls, sporangia free of the sporophyll pedicel, and bisaccate, protosaccate pollen suggests that Leastrobus represents a member of the “Voltziales” most similar to the European genus Ruehleostachys.