Deep subtidal marine plants from the Northwestern Hawaiian Islands: New perspectives on biogeography

In the past 15 years, scientific focus on the marine flora of the Northwestern Hawaiian Islands (NWHI) has intensified, resulting in a doubling of the total number of known species. In 1989, 205 species were recorded; as of January 2005, 353 species have been published for the NWHI. Over 5,100 specimens collected from Midway Atoll and other atolls, reefs, islands, and deep-water sites in the NWHI have shown a marine flora with geographic distribution patterns different from any known similar- sized area in the Pacific. Several new species of macroalgae have been described, including Dudresnaya babbittiana (Rhodophyta), Kallymenia thompsonii (Rhodophyta), Hydroclathrus tumulis (Phaeophyta), Padina moffittiana (Phaeophyta), and Codium hawaiiense (Chlorophyta). Since 1989, numerous macroalgal and two seagrass species have been documented as records of species new to the NWHI, including Kallymenia sessilis, Desmarestia ligulata, Nereia intricata, Sporochnus moorei, Caulerpa antoensis, C. cupressoides, C. elongata, C. microphysa, Halophila decipiens, and H. hawaiiana. Although the Hawaiian Archipelago is considered part of the Tropical Indo-West Pacific phytogeographic region, the NWHI's mixture of tropical species, cold-temperate species, species with disjunct distributions, and endemic species suggests alternative biogeographic patterns and dispersal routes.