Search

Premise: Pandanus Parkinson (Pandanaceae) is a large genus of paleotropical tree-like monocots. Previous studies using small DNA regions questioned the monophyly of the seven Pandanus subgenera, but low phylogenetic branch support hindered further investigations. We aimed to (1) test Pandanus subgeneric monophyly, (2) identify clade morphological synapomorphies, (3) investigate correlations between leaf anatomy of water storage tissue and climatic differentiation across clades, and (4) construct hypotheses on the genus' spatiotemporal history., Methods: We sequenced 50 Pandanus species using genome skimming and reconstructed plastomes with MITObim. We inferred partitioned RAxML phylogenetic trees to test subgeneric monophyly using Shimodaira-Hasegawa tests. We inferred a partitioned dated BEAST phylogenetic tree used for ancestral state reconstructions of morphological traits. Phylogenetic clades were used to compare climatic (Bioclim) and soil (UNESCO Digital Soil Map) conditions using random forests. We correlated present morphology and climatic niche with past climate events., Results: Our phylogenetic analyses revealed two clades and four subclades. Only subgenus Coronata was monophyletic. Staminate synapomorphies were identified for three subclades. Hypertrophied and hyperplasic water-storage tissue was a synapomorphy for clade II, correlating with more seasonal temperature and precipitation regimes and more well-draining soil. Clades differentiated during the advent of the Southeast Asian monsoon in the early Miocene, whereas subclades differentiated during the Miocene Thermal Maximum., Conclusions: Pandanus subgeneric classification needs to be revised. Hypertrophied hyperplasic water-storage tissue is a key trait in Pandanus evolution, possibly explaining climatic and biogeographic patterns because it is key to maintaining photosynthesis during periods of hydric stress., (© 2025 Botanical Society of America.)

Premise: The economically important, cosmopolitan soapberry family (Sapindaceae) comprises ca. 1900 species in 144 genera. Since the seminal work of Radlkofer, several authors have attempted to overcome challenges presented by the family's complex infra-familial classification. With the advent of molecular systematics, revisions of the various proposed groupings have provided significant momentum, but we still lack a formal classification system rooted in an evolutionary framework., Methods: Nuclear DNA sequence data were generated for 123 genera (86%) of Sapindaceae using target sequence capture with the Angiosperms353 universal probe set. HybPiper was used to produce aligned DNA matrices. Phylogenetic inferences were obtained using coalescence-based and concatenated methods. The clades recovered are discussed in light of both benchmark studies to identify synapomorphies and distributional evidence to underpin an updated infra-familial classification., Key Results: Coalescence-based and concatenated phylogenetic trees had identical topologies and node support, except for the placement of Melicoccus bijugatus Jacq. Twenty-one clades were recovered, which serve as the basis for a revised infra-familial classification., Conclusions: Twenty tribes are recognized in four subfamilies: two tribes in Hippocastanoideae, two in Dodonaeoideae, and 16 in Sapindoideae (no tribes are recognized in the monotypic subfamily Xanthoceratoideae). Within Sapindoideae, six new tribes are described: Blomieae Buerki & Callm.; Guindilieae Buerki, Callm. & Acev.-Rodr.; Haplocoeleae Buerki & Callm.; Stadmanieae Buerki & Callm.; Tristiropsideae Buerki & Callm.; and Ungnadieae Buerki & Callm. This updated classification provides a backbone for further research and conservation efforts on this family., (© 2021 The Authors. American Journal of Botany published by Wiley Periodicals LLC on behalf of Botanical Society of America.)