Hidden in Plain Sight: A New Pink-Fruited Species of Actaea L. (ranunculaceae) from New York

We describe Actaea rhodostigma sp. nov. J.T.Scholten, A.K.Sprenger & C.D.Specht, a newly recognized, pink-fruited species from New York, USA. Morphological analyses of more than 100 individuals per species revealed consistent diagnostic traits-including pink fruits, pink stigmas, and reddish sepal apices-that reliably distinguish A. rhodostigma from its congeners. Phenological surveys demonstrated staggered flowering times across populations, with A. rhodostigma consistently blooming between A. rubra and A. pachypoda, whereas floral scent and visitor observations showed divergent scent profiles and pollinator assemblages that likely contribute to reproductive isolation. Genomic analyses, including phylogenetic inference, Patterson's D-statistics, PCA, and admixture detection, recovered A. rhodostigma as a cohesive lineage sister to A. pachypoda, with no evidence of species-wide hybrid ancestry; localized signals of admixture were restricted to populations in sympatry. Together, these results establish A. rhodostigma sp. nov. as an independently evolving lineage and underscore the importance of integrative approaches for resolving species boundaries in morphologically complex groups.