Cypselae of Canary Island Tolpis (Asteraceae: Cichorieae): Populational Variation, Biogeography, and Taxonomic Utility

Abstract

Tolpis Adans. (Asteraceae: Cichorieae) is a small monophyletic clade in the Macaronesian archipelagos, the larger of two subclades occurring in the Canary Islands. Variation in setae number and body lengths of cypselae, which ostensibly function in dispersal and establishment, were studied to assess their biogeographic and ecological implications, and their taxonomic utility. The Tukey post-hoc test assessed differences in cypselae among populations on each island, means among islands, and differences among taxa. El Hierro populations share the same Tukey group for both characters; there are differences among populations on both La Gomera and La Palma. Setae number is variable on geologically complex Tenerife with five Tukey groups in the sampling from different substrates, areas of the island, and taxonomic designations. Mean values for cypsela characters do not differ among El Hierro, La Gomera, and La Palma; Tenerife has larger cypselae and higher setae numbers than the other three islands. Population variation in cypselae limits their use as characters for delimiting taxa; however, variation associated with geological substrates and potential dispersibility were noted. The commonly reported larger cypselae of insular lineages compared to closest continental relatives are not seen in Canarian Tolpis.