Polyploidy and new chromosome counts in Pseudognaphalium Kirp. (Compositae: Gnaphalieae)

ABSTRACT

Pseudognaphalium Kirp. (Compositae: Gnaphalieae) comprises approximately 90 species and it has a worldwide but fragmented distribution. This study provides a total of 20 chromosome counts, nine of which are the first report for a species, and the rest are confirmation of previous reports. With the addition of these data to the previously published reports, the chromosome numbers for a total of 32 species of the genus Pseudognaphalium are now available. Considering all chromosome data available at present, c.22% of the species are diploids and c.78% are polyploids, mainly tetraploids. African and Asian species are predominantly diploid whereas the vast majority of the American species are tetraploid, suggesting that polyploidy played a key role in the colonization of the American continent by the genus Pseudognaphalium.

KEYWORDS:

• America
• Asteraceae
• chromosome number
• Compositae
• Gnaphalieae
• polyploidy
• Pseudognaphalium

Acknowledgements

M. G.-C. greatly appreciates Sebastián Arrabal’s help, enthusiastic support, dedication and joy in all the shared field expeditions. David Juárez and Sebastián Teillier provided very valuable help and advice for field trips and plant collections, and Santiago Andrés provided material from his field collections; all of them are gratefully acknowledged. We thank Susana Magallón for organizing the stay of M. G.-C. at the “Universidad Nacional Autónoma de México”. We thank the staff of the herbaria of “Institut Botànic de Barcelona” (BC, Neus Nualart), “Universidad de Concepción” (CONC, Alicia Marticorena), “Universidad Nacional Autónoma de México” (MEXU, David Gernandt and José Luis Villaseñor), Missouri Botanical Garden (MO, John Pruski), “Universidad de Salamanca” (SALA, Francisco Javier Hernández), “Museo Nacional de Historia Natural de Santiago de Chile” (SGO, Gloria Rojas), University of Texas at Austin (TEX, George Yatskievych), and Smithsonian Institution (US, Ingrid P. Lin) for kindly attending M. G.-C. and for providing specimens and/or institutional support for plant collections. Laia Guàrdia provided the microscope and camera, and the technical support necessary for using them. Joan Prunera provided technical support for some of the chromosome counts. Samuel Pyke is acknowledged for the English correction. Two anonymous reviewers contributed to improve the paper.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

M. G.-C. benefited from a “Systematics Research fund” from the Systematics Association and the Linnean Society of London and a “Beca Iberoamérica Jóvenes Profesores Investigadores” from “Banco Santander”, which partly financed the stays and field work in Chile and Mexico, respectively. The Catalan government (“Ajuts a grups consolidats” 2014-SGR 514) partly financed this work.