A new genus and species of Anacardiaceae fossil wood from Ituzaingó Formation (late Miocene?), Entre Ríos, Argentina

FRANCO, M. J.; MARTÍNEZ MARTÍNEZ, C.; BREA, M.; MOYA, E.

San Luis

Workshop; Reunión Anual de Comunicaciones de la Asociación Paleontológica Argentina; 2017

Universidad Nacional de San Luis

The main aim of this contribution is to describe a new genus and species of Anacardiaceae fossil wood found in the sediments of Ituzaingó Formation, an important fluvial deposit of the Paleoparaná River. The materials (CIDPALBO-MEG 41 and CIDPALBO-MEG 46) were recovered at the Toma Vieja fossiliferous locality, Entre Ríos Province, and are preserved as siliceous cellular permineralization. They were prepared for microscopic examination by surface polishing and obtaining thin sections (cross, longitudinal tangential and longitudinal radial sections). These fossil woods have diagnostic features that allow its separation from other previously described Anacardiaceae fossil taxa: diffuse to semi-ring porous; vessels without arrangement or in diagonal pattern, solitary, in radial multiples of 2?3 (4?5) or in clusters; intervessel pits bordered and alternate to opposite; abundant tyloses; simple perforation plate; mostly 1?3 seriate rays, also multiseriate, heterocellular, composed by procumbent and upright cells; some multiseriate rays with schizogenous canals higher than 500 μm; axial parenchyma paratracheal vasicentric, confluent, aliform and apotracheal terminal; and the presence of prismatic crystals in chambered upright and/or square and procumbent ray cells. Taking in account to this features, this new fossil genus and species is related to extant Metopium Browne, an evergreen to semi deciduous medium size tree, with a distribution ranging from the West Indies to Florida, Mexico and Central America. This new finding extends the age, as well as the geographical record, of this lineage among Anacardiaceae.