Inclusion of the Vietnamese endemic genus Grushvitzkya in Brassaiopsis (Araliaceae): evidence from nuclear ribosomal ITS and chloroplast ndhF sequences

Abstract

The phylogenetic position of the recently described monotypic Vietnamese genus Grushvitzkya is evaluated using nuclear ribosomal ITS and chloroplast ndhF sequence data. Grushvitzkya stellata has often been considered as intermediate between Brassaiopsis and Trevesia, but differs in having a 5-locular ovary rather than a 2- or 6–16-locular ovary, respectively. The molecular data indicate that Grushvitzkya is deeply nested within Brassaiopsis and has a close relationship with B. phanrangensis from central and southern Indochina, and B. stellata from the regions bordering China and Vietnam. The Kimura 2-parameter distances of the ITS sequences between G. stellata and B. phanrangensis and B. stellata are 0.403 and 0.945%, respectively. Furthermore, G. stellata and B. phanrangensis have an identical ndhF sequence profile. Grushvitzkya stellata differs from B. stellata by a single nucleotide in their ndhF sequences. The available evidence is compatible with the hypothesis that Grushvitzkya diverged recently from B. phanrangensis and B. stellata. Although these three closely related species all possess stellate trichomes, G. stellata and B. phanrangensis have highly similar trichome micromorphology, with almost no difference in size, shape and branching pattern, supporting a very close relationship between the two taxa. The higher number of locules in the ovary of Grushvitzkya appears to be a secondary increase despite earlier interpretations that higher numbers are evolutionarily primitive. Grushvitzkya is herein merged with Brassaiopsis; because the combination B. stellata is occupied, a new name, Brassaiopsis grushvitzkyi, is proposed. © 2003 The Linnean Society of London, Botanical Journal of the Linnean Society, 2003, 142, 455–463.