Toward a New Generic Delimitation in Polygalaceae III: Chamaebuxus, Chodatia, Heterosamara, and Paivanthus

José Floriano Barêa Pastore — 2026-03-06

The Chamaebuxus alliance (Polygalaceae) comprises the Old World genera Heterosamara Kuntze, Chamaebuxus Tourn. (formerly known as Polygaloides Haller), and Polygala L. subg. Chodatia Paiva and represents the last unresolved lineage of Polygala s.l. that has not yet been comprehensively analyzed in a phylogenetic study. Based on phylogenetic and morphological evidence, we accommodate these taxa into four distinct genera: Chamaebuxus, Chodatia (Paiva) J. F. B. Pastore, comb. & stat. nov. (elevated to genus rank), Heterosamara, and Paivanthus J. F. B. Pastore, gen. nov. Phylogenetic trees were inferred using target enrichment data with Angiosperms353 probes, complemented by data from the maternally inherited plastid loci and the biparentally inherited nrITS region. A strongly supported topological incongruence was observed between the plastid and nuclear datasets for the African genus Paivanthus, which was recovered as sister to Chodatia in plastid analyses, but as sister to the Asiatic genus Heterosamara in nuclear analyses. This incongruence suggests a likely hybrid origin for the African lineage formerly included in Heterosamara. Here, Polygala subg. Chodatia is raised to generic rank, encompassing the species formerly alternatively assigned to Polygala sect. Arillus S. K. Chen. Within Chamaebuxus, we recognize two sections: the Old World section Chamaebuxus and the North American monotypic section Triclisperma (Raf.) J. F. B. Pastore. Two genera are now recognized as having heteropolar pollen: Heterosamara s. str. and Paivanthus, which includes African species previously assigned to Heterosamara. The genus Heterosamara is further subdivided into five sections: section Ecristata J. F. B. Pastore (newly described), section Heterosamara, section Saxicola S. K. Chen, section Spathulata J. F. B. Pastore (newly described), and section Villososperma C. Y. Wu & S. K. Chen. A taxonomic key is provided for the genera Chamaebuxus, Chodatia, Heterosamara, Paivanthus, and Polygala, along with their infrageneric taxa. Photographic plates, a distribution map, 15 new lectotypes, six second-step lectotypes, two new heterotypic synonyms, 41 new combinations, and nomenclatural notes are also presented.

Rubiacearum Americanarum Magna Hama Pars LV. Overview with a Revised Circumscription of Palicourea sect. Heteropsychotria (Palicoureeae)

Charlotte M. Taylor — 2026-04-28

Many of the species classified in Psychotria L. subg. Heteropsychotria Steyerm. have been shown to belong to Palicourea Aubl. based on morphological and molecular characters. Here, species corresponding to Psychotria sect. Heteropsychotria Steyerm. are studied. This section is circumscribed here differently than by Borhidi, to include 29 species found from Mexico and the Antilles to southeastern Brazil with centers of diversity in northeastern South America and the Greater Antilles. This section is not easily diagnosed morphologically because its features are ancestral and widespread in Palicourea, but it can be characterized generally by the combination of stipule form, inflorescence arrangement, and corolla and fruit details. Here several species have revised taxonomic circumscriptions and names, seven new nomenclatural combinations are published, seven names are lectotypified, and four new species are described: Pal. laxivenulosa C. M. Taylor and Pal. pseudovenulosa C. M. Taylor are found in the Andes of Ecuador, Peru, and Bolivia, and Pal. chiribiquetensis C. M. Taylor and Pal. hopkinsiana C. M. Taylor are found in the central to western Amazon basin.

Annals of the Missouri Botanical Garden

Toward a New Generic Delimitation in Polygalaceae III: Chamaebuxus, Chodatia, Heterosamara, and Paivanthus

Rubiacearum Americanarum Magna Hama Pars LV. Overview with a Revised Circumscription of Palicourea sect. Heteropsychotria (Palicoureeae)