REDESCRIPTION OF SOLANUMXYLON PARANENSIS, LATE MIOCENE OF PARANÁ FORMATION (ENTRE RÍOS, ARGENTINA): A RELIABLE FOSSIL WOOD OF SOLANACEAE

Abstract

The diagnostic anatomical features of Solanumxylon paranensis were restudied using light and scanning electron microscopy. The holotype was collected from Paraná Formation (late Miocene) in Toma Vieja fossil locality (Entre Ríos, Argentina). The taxonomic position and affinity of the Solanumxylon are discussed, and its diagnosis is extended. The following features suggest affinities with the Solanaceae: diffuse porosity, vessels solitary, and less commonly in radial multiples and in clusters, simple perforation plates, alternate intervessel pits, vessel-ray pits similar to intervessel pits and/or apparently simple, pits rounded in outline, rays 1–4 cells wide, all ray cells procumbent or body ray cells procumbent with one row of upright and/or square marginal cells, fibers with simple to minutely bordered pits, septate fibers present, scanty paratracheal parenchyma. This paper provides more details about the systematic assignment of Solanumxylon paranensis within the Solanaceae and its affinity with Solanum. This fossil can be used in phylogenetic studies of the family/genus, increasing our knowledge of Solanum history and diversity.