Two new fossil matoniaceous stem genera from Tasmania, Australia

Abstract

Two new genera, Tasmanopteris and Heweria, from Tasmania are the first definite permineralized rhizomes assignable to the Matoniaceae. Tasmanopteris richmondii sp. nov., of mide-Mesozoic age, is from the Lune River site in southwestern Tasmania and is composed of four or more annular solenostelos separated by cortices with an inner mesarch xylem ring and outer exarch xylem rings. Secretory canals occur in the cortices between the protoxylem clusters of its outer xylem rings. The specimen of Heweria kempii sp. nov., which is very similar to extant Matonia, was collected from a Lower Tertiary conglomerate in central Tasmania but was reworked from older sediments. Anatomically, the rhizomes of Heweria consist of 3–6 annular solenosteles with the inner and middle xylem rings being mesarch, whereas the outer ring is exarch. Roots arise opposite the protoxylem clusters of the outermost ring. Epidermal hairs on the stems of this genus are like those of living Matonia in being attenuate, uniseriate, and multicellular. Associated venation pattern of partially preserved leaves, isolated sporangia, annuli, and spores in this specimen provide additional support for the relationships of this fossil to modern Matonia.