Redescription and reassignment of the fossil wood Menendoxylon piptadiensis from the Pliocene Andalhuala Formation, South America

Abstract

A new study of the holotype of Menendoxylon piptadiensis has revealed that this taxon possesses many diagnostic anatomical features not associated with Leguminoseae-Mimosoideae. In this contribution, it was described again and is re-assigns to Rauvolfioideae-Apocynaceae. This petrified wood recovered from the Pliocene Andalhuala Formation from Valle de Santa María (Catamarca, Argentina) and is the first fossil wood with affinity to Apocynaceae from South America. The systematic is based on anatomical data and supported by statistical analysis. A PCA and cluster analysis of 6 woods and 21 characters was performed to confirm the taxon delimitation. The eco-anatomical characteristics and the Nearest Living Relatives (NLRs) indicate a warmer and more humid climate in the region during the Pliocene, probably associated with tropical forests. The most related extant is Parahancornia and these supports the hypothesis that genus was more widespread in the past.