Structurally Preserved Sphenophytes From the Triassic of Antarctica: Vegetative Remains of Spaciinodum, Gen. Nov.

Abstract

Sphenophyte remains of Early‐Middle Triassic age are described from silicified peat collected in the Transantarctic Mountains of Antarctica. The new sphenophyte, Spaciinodum collinsonii sp. nov., is represented by ribbed, jointed stems with characteristic pith and carinal canals. Stems are relatively small, ranging from 1.8–3.0 mm in diameter, lack secondary tissues, and are characterized by vallecular canals that are restricted to nodal regions. The internodal vascular system consists of 12–18 collateral bundles which alternate between successive internodes. A complete vascular ring is present in the nodal region and is surrounded by a continuous double endodermis. Xylem is endarch and composed of elements ranging from annular to reticulate. The Antarctic sphenophyte is compared with other Gondwana fossil articulates and extant Equisetum. Superficial stomata suggest affinities with modern Equisetum subgenus Equisetum; however, some anatomical differences preclude assignment with living species.

A new hybrid horsetail Equisetum×lofotense (E. arvense×E. sylvaticum, Equisetaceae) from Norway

“…Such fossils are usually summarized in the genus Equisetites , but in some cases they can hardly be separated from modern Equisetum , and therefore, have occasionally been placed in the genus Equisetum by some authors (Gould 1968, Stanich et al 2009). Recently, additional fossil genera belonging to the Equisetaceae were described from the Mesozoic: Spaciinodum (Osborn and Taylor 1989, Osborn et al 2000, Ryberg et al 2008) and Asinisetum (Weber 2005, 2008).…”