Maderas fósiles de Combretaceae de la Formación El Palmar (Pleistoceno), Entre Ríos, Argentina

Abstract

Petrified wood of a new species of Terminalioxylon Schonfeld from the El Palmar Formation (Upper Pleistocene), Concordia, Entre Ríos, Argentina, is described. The comparison with members of Combretaceae shows that Terminalioxylon concordiensis nov. sp. is different from other known fossil species and is similar to the extant genus Terminalia L. and close to T. triflora (Gris.) Lillo. Terminalioxylon concordiensis presents growth rings delimited by small vessels and narrow lines of terminal parenchyma. Vessels have diffuse porous, are mostly solitary, sometimes in radial multiple series of 2-3, rarely 4 elements, simple perforation plate. Ray system is homogenous. Rays are homocellular, frecuently uniseriate, rarely uniseriate with biseriate portion. Fibres are hexagonal, septate and abundant. Apotracheal axial parenchyma is diffuse and diffuse-in-aggregate, and paratracheal usually vasicentric, complete to aliform, rarely confluent and with terminal parenchyma bands associated with 2-4 vessels. Cristals are of two types and very frequent in rays and cells ofaxial parenchyma. Intercellular canals of traumatic origin are surrounded by parenchyma tissue.