RAZ, LAUREN*, VICTOR A. ALBERT, AND TIMOTHY J. MOTLEY. The New York Botanical Garden, Bronx, NY 10458-5126. - Molecular systematics of Hawaiian Chamaesyce (Euphorbiaceae).
The genus Chamaesyce consists of approximately 250 species with
a cosmopolitan distribution. The genus is best represented in the New
World (ca. 80% of the species) and exhibits the highest amount of
species diversity in Mexico. There are 22 species of
Chamaesyce in Hawai`i. Fifteen species are endemic to the
archipelago and seven are thought have been introduced and have become
naturalized. The Hawaiian endemics are composed of semi-woody to
arborescent taxa that are reputably derived from a single ancestor of
the Pacific C. atoto complex. Cladistic analyses of nucleotide
sequence data from the nuclear ITS and 5S-NTS loci were used to
examine relationships among and between native and introduced species.
Based on the species included in this study: (1) the Hawaiian taxa
form two distinct clades, one containing arborescent taxa and the
other containing semi-woody, non-arborescent taxa; (2) the herbaceous
C. prostrata, generally considered naturalized in Hawai`i,
occurs within the clade of non-arborescent Hawaiian taxa. This
suggests that the Hawaiian species of Chamaesyce may not be
monophyletic and that C. prostrata shares a common ancestor
with the non-arborescent species. This research is supported by the
Lewis B. and Dorothy Cullman Foundation.
Key words: 5S-NTS, Chamaesyce, Hawai`i, ITS