Reconsidering a disjunct distribution: Molecular and morphological evidence for two evolutionarily distinct lineages in Protea mundii Klotsch

• Protea mundii has two evolutionarily distinct groups.
• The two evolutionary groups do not appear to be sister to each other.
• Genetic similarities between one group and another species is due to shared ancestry.
• The two units can can be distinguished based on leaf and fruit characters.
• Species designation in a rapidly speciating group presents unique challenges.

Protea mundii Klotsch (Proteaceae) has a disjunct distribution, with a large range in the Eastern Cape between Knysna and Port Elizabeth, and a smaller one in the Western Cape between Betty's Bay and Hermanus. Here, we provide population genetic and morphological evidence that populations in the two ranges belong to two distinct evolutionary lineages. Using 10 microsatellite loci, we show not only that the populations in the two ranges are genetically distinct but also that they may not even be sister to each other. We measured floral and leaf traits and determined that despite broad morphological similarities, the two lineages can be distinguished from each other by the width of their leaves (western — wider leaves, eastern — narrower leaves), the angle of the leaf bases (western — less acute, eastern — more acute), and the mass of their seeds. We conclude that these two lineages should be treated as independent entities for management and conservation purposes.