Divergence estimates of tetrachondra hamiltonii and T. Patagonica (tetrachondraceae) and their implications for austral biogeography

The enigmatic genus Tetrachondra has been included variously in the Boraginaceae, Lamiaceae, Scrophulariaceae, or recognised as the distinct family Tetrachondraceae. Two species with a disjunct distribution are included in the genus: T. hamiltonii is confined to New Zealand, and T. patagonica is confined to South America. New Zealand and south America Once f0m‐d part of Gondwana, but separated aPProximatelY 80 million Years ago. In a parsimony analysis of rbcL sequences, T. hamiltonii and T. patagonica form a distinct, well‐supported clade that diverged early in the evolutionary history of the large angiosperm order Lamiales. Polypremum Procumbens emerges as their sister group. While there are no known fossils of Tetrachondraceae, fossils from related families in the Lamiales suggest that the Tetrachondra/Polypremum lineage may have evolved during the Paleocene. The rbcL sequences of T. hamiltonii and T. patagonica are virtually identical, however, suggesting a more recent divergence during the Pleistocene for these two species. Thus, their present disjunct distribution reflects long‐distance dispersal rather than vicariance.