Morphologically similar but genetically distinct: on the differentiation of Syzygiella concreta and S. perfoliata (Adelanthaceae subfam. Jamesonielloideae)

Abstract

The generitype Syzygiella perfoliata and S. concreta share the same gross morphology but are only loosely related in molecular phylogenies. Based on an nrITS maximum likelihood phylogeny we identify accessions belonging to either the Syzygiella concreta or the S. perfoliata lineage. We use these DNA vouchers to recircumscribe both species and present morphological characters that allow for their identification. Differences have been seen in the development of the stem cortex, the insertion of the leaves, presence or absence of rudimentary amphigastria, size and shape of the leaf cell wall trigones, and papillosity of the leaf cuticle.