First record of Sahnioxylon Bose & Sah from South America (Upper Jurassic – Lower Cretaceous of Argentine Patagonia)

Records of Mesozoic fossil woods with scalariform pits in radial walls are scarce worldwide and restricted to a few genera. Sahnioxylon Bose & Sah is a fossil genus with scalariform pits in radial walls and, until now, a limited and restricted distribution to Antarctica, India and possibly eastern Asia. In addition, Sahnioxylon is possibly associated with Bennettitales. Three silicified wood specimens from the Upper Jurassic to Lower Cretaceous interval, collected at the southern margin of Fontana Lake, Chubut Province, Argentina, were described and assigned to Sahnioxylon . Two wood specimens have pith and primary xylem attached. The pith is composed of polygonal to circular parenchyma cells and idioblasts. The primary xylem is poorly preserved and occasionally observed. The secondary xylem is composed of tracheids and parenchyma rays. It has distinct growth ring boundaries, with latewood usually wider than earlywood. Tracheids have (uni‐ or biseriate) araucarian to scalariform pits in radial walls. Cross‐fields have 1–9 contiguous simple pits. Rays are uniseriate to partially biseriate, with pitting in the horizontal and end cell walls. Additionally, hyphae inside the wood suggest plant–fungus interactions. This record of Sahnioxylon in Argentine Patagonia expands the distribution of this genus in Gondwana and is the first in South America.