Revisiting the Taxonomy of the Widespread Neotropical Moonseed Abuta grandifolia: Insights from the Morphological and Molecular Data

Abstract

Species that are geographically widely distributed and morphologically variable present considerable challenge when eval­uating their taxonomic boundaries. The Neotropical moonseed Abuta grandifolia (Mart.) Sandwith species group is one example of such a widespread and morphologically variable nominal taxon. The species group is widely distributed in the Amazon basin, Guianas, and extra-Amazon region in Brazil. It is well known for its various ethnobotanical uses, and although earlier prelimi­nary morphological investigations suggested that it may comprise more than one species, its taxonomic limits have remained uncertain.

In this study, we explore taxonomic boundaries within the Abuta grandifolia species group by integrating morphological and molecular data. Variation in vegetative and reproductive morphological traits was investigated at a continental scale among our four pre-established morphological groups. Molecular variation was explored among co-occurring morphological groups at local and regional scales in Western Amazonia in Peru. Our morphometric analysis clearly distinguished two of the four morpholog­ical groups where significant traits differentiating them are mostly vegetative. Phylogenetic analyses based on four markers (ITS, trnL-F, trnH-psbA, and rps16) recovered four clusters that correspond to the four groups. Our results confirm previous studies regarding the presence of distinguishable taxonomic units within the widespread A. grandifolia s.l. These may corre­spond either to species already described and thus in need of reinstatement or to new species in need of description.