Clarifying the identity of the Cleistes rosea complex (Orchidaceae) based on integrative taxonomy

Abstract

Cleistes rosea and 10 other taxa comprise a complex widely distributed in various open vegetation types from eastern South America to Panama. The taxonomic identity of most of these taxa is unclear and their relationships with C. rosea have never been satisfactorily discussed or tested. Here, we employ molecular phylogenetics, morphometrics and morphological, ecological and geographic distribution data to investigate the relationships and taxonomy of Cleistes rosea and related species. Our results confirm that Cleistes rosea and Cleistes castaneoides are sister species and although highly similar in general floral morphology, they differ in vegetative characters, distribution, habitat, floral scent, and lip characters. Both species show local variations regarding floral characters, particularly the flower colour, and such differences were used here to delimit infraspecific taxa within the C. rosea/C. castaneoides clade. While C. rosea var. guianensis var. nov. is restricted to French Guiana, and C. rosea var. buenaventurae stat. & comb. nov. is restricted to low altitudes on the western side of the Cordillera Occidental in the Chocó region of Colombia, C. castaneoides var. castaneoides and C. castaneoides var. augusta comb. nov. are sympatric throughout their distribution. Cleistes abdita, formerly known as C. rosea f. pallida, is similar to C. castaneoides but distinguished by the smaller flowers and restricted distribution to Amazonian savannas. Cleistes rosea is distributed throughout the north of the Andes and northern South America. In turn, C. castaneoides occurs mainly in South-eastern and Central-western Brazil. Still, the distribution of these three species overlaps in the Guiana Shield, where the differentiation between them is less evident. Our results provide evidence of the plasticity of the floral morphology of Cleistes, especially the lip, and highlight that hitherto neglected characters, such as vegetative morphology, habitat, and floral scent, are particularly informative for the characterization of species and taxonomy of the genus.

Key words:

• grasslands
• infraspecific variation
• morphology
• morphometrics
• Neotropics
• online biodiversity databases
• Pogonieae
• systematics
• Vanilloideae

Acknowledgements

We thank Marie Aucourd for kindly providing us with the illustrations of C. rosea var. guianensis, Eddley Pessoa, Ismael Oliveira, Julio Betancur (COL), Dairon Cárdenas (COAH), Alejandro Zuluaga (CUVC), Felipe Cardona (HUA), Robinson Galindo, Camilo Ernesto Echeverri Garcia, Sonia Camargo, Alexey Yakovlev, Gustavo A. Romero-González, Germán Carnevali, Michael Polansky (W) and Jurriaan de Vos (RENZ) for providing photographs, field information or references, Christian Bräuchler for help in obtaining the type image of C. lehmannii and translation of the label data, Marco Pellegrini (Scientifik Traduções) for revising the English and helpful comments, the curators and staff of the herbaria for specimen loans, images, or for providing access to their collections and an anonymous reviewer and the associate editor for helpful suggestions and improvements in the manuscript. JANB also acknowledges a research productivity grant (process 304485/2019-5) received from Conselho Nacional de Desenvolvimento Científico e Tecnológico, Brazil (CNPq).

Disclosure statement

The authors report there are no competing interests to declare.

Supplemental material

Supplemental material for this article can be accessed here: https://dx.doi.org/10.1080/14772000.2023.2207575.

Associate Editor: Dr Aelys Humphreys