Abstract
Two new species of the recently revised genus Oparanthus (Asteraceae, Subtribe Coreopsidinae) were discovered during the National Tropical Botanical Garden/Smithsonian Institution 1997 expedition to the Marquesas Islands. Oparanthus woodii W. L. Wagner & Lorence, sp. nov. is known from a single population on the island of Nuku Hiva, and Oparanthus tiva W. L. Wagner & Lorence, sp. nov. is known only from Tahuata. Small domatia with a tuft of hairs occur in Oparanthus tiva (and the previously known Oparanthus hivoanus), and similar but naked domatia are found occasionally in Oparanthus woodii. Domatia are of exceedingly rare occurrence in Asteraceae. Both new species are extremely rare and are considered critically endangered (CR) as are the other four species of the genus.
Highlights
Ongoing investigation of the vascular flora of the Marquesas Islands has been facilitated through a collaboration between National Tropical Botanical Garden (NTBG), Smithsonian Institution (SI), and the Délégation à la Recherche Papeete, Tahiti, French Polynesia
Domatia are essentially absent in the family, so domatia in O. tiva should be investigated further to understand the ecological significance
When domatia were discovered in O. tiva, we reexamined the other species of the genus and those of the closely related genus Fitchia
Summary
Ongoing investigation of the vascular flora of the Marquesas Islands has been facilitated through a collaboration between National Tropical Botanical Garden (NTBG), Smithsonian Institution (SI), and the Délégation à la Recherche Papeete, Tahiti, French Polynesia. Known Marquesan species and two from Rapa Island (Shannon and Wagner 1997). (Carlquist 1974; Shannon and Wagner 1997) These relationships were not supported by ITS study of the Coreopsideae by Kimball and Crawford (2004). According to their phylogenetic results Fitchia and Oparanthus are sister genera and share a common ancestor with two Caribbean genera, Narvalina Cass. Wagner unpubl.) to further examine the biogeographic patterns in this lineage of two genera with no affinities to other Pacific Asteraceae but which represent an interesting biogeographic disjunction with two genera of the Caribbean This unpublished phylogenetic analysis of Oparanthus and Fitchia utilized nuclear ribosomal gene regions (ITS, ETS, and 5S-NTS). Marquesan species of Oparanthus meet the IUCN criteria by having known ranges less than 100 km, an area of occupancy of less than 10 km, continuing decline in the quality of habitat
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