Cytogenetics, Typification, Molecular Phylogeny and Biogeography of Bentinckia (Arecoideae, Arecaceae), an Unplaced Indian Endemic Palm from Areceae

SIMPLE SUMMARY: Bentinckia is an Indian endemic genus belonging to the tribe Areceae (Arecaceae). This genus contains two species, B. condapanna and B. nicobarica, and both need to be conserved as they come under the threatened category. Bentinckia, along with nine genera, remains unplaced in Areceae. The members of the unplaced Areceae show characteristics corresponding to all the subtribes. Therefore, morphologically it is difficult to assign any subtribes to these genera. Many molecular phylogenetic analyses have reported the relationships within Areceae. However, all of these are unable to show confident position and support for the species. In the present article, we constructed the molecular phylogeny of Areceae based on an appropriate combination of chloroplast and nuclear loci that satisfactorily depicts the phylogenetic positions of all species from Areceae. Phylogeny and evolutionary history disclose that Bentinckia together with unplaced Clinostigma and Cyrostachys show a close relationship with the subtribe Arecinae and might have originated in Eurasia and India. In addition, this study reports a taxonomic revision of Bentinckia. In addition, it provides a new chromosome number (cytotype), i.e. 2n = 30 for B. condapanna. This study will form the very basis for assessing and refining the systematic position of all the species from the tribe Areceae. ABSTRACT: Bentinckia is a genus of flowering plants which is an unplaced member of the tribe Areceae (Arecaceae). Two species are recognized in the genus, viz. B. condapanna Berry ex Roxb. from the Western Ghats, India, and B. nicobarica (Kurz) Becc. from the Nicobar Islands. This work constitutes taxonomic revision, cytogenetics, molecular phylogeny, and biogeography of the Indian endemic palm genus Bentinckia. The present study discusses the ecology, morphology, taxonomic history, distribution, conservation status, and uses of Bentinckia. A neotype was designated for the name B. condapanna. Cytogenetical studies revealed a new cytotype of B. condapanna representing 2n = 30 chromosomes. Although many phylogenetic reports of the tribe Areceae are available, the relationship within the tribe is still ambiguous. To resolve this, we carried out Bayesian Inference (BI) and Maximum Likelihood (ML) analysis using an appropriate combination of chloroplast and nuclear DNA regions. The same phylogeny was used to study the evolutionary history of Areceae. Phylogenetic analysis revealed that Bentinckia forms a clade with other unplaced members, Clinostigma and Cyrostachys, and together they show a sister relationship with the subtribe Arecinae. Biogeographic analysis shows Bentinckia might have originated in Eurasia and India.