RESUMEN
Meryta pastoralis F. Tronchet & Lowry, a new species from the island of Hiva Oa in the Marquesas archipelago, is described and illustrated. It differs from other Polynesian members of the genus by its fully free ovaries, a feature shared with one other species found in the region, Meryta choristantha (native to the Austral Islands), distinguished by its ovate to spatulate (vs. elliptic to obovate) leaf shape. A preliminary risk of extinction assessment indicates that Meryta pastoralis is Critically Endangered.
RESUMEN
Phylogenetic studies were conducted to evaluate interspecific relationships in Osmorhiza (Apiaceae: Apioideae) using sequences of the ITS regions of nuclear ribosomal DNA, the chloroplast ndhF gene, and two noncoding regions (trnL intron, and trnL [UAA] 3' exon-trnF [GAA] intergenic spacer). All data sets suggest the monophyly of the New World taxa and showed that Osmorhiza aristata from Asia is relatively divergent from other members of the genus, even though it is morphologically similar to the eastern North American O. claytonii and O. longistylis. The ITS and chloroplast DNA trees differ in the relationships among the New World taxa, especially the phylogenetic position of O. occidentalis, O. glabrata, and O. depauperata. The lack of congruence between the two data sets may be a result of hybridization or introgression. Although there is high discordance between nrITS and two chloroplast DNA data sets, the latter two show similar topologies.
