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- Genetic diversity of Gibsmithia hawaiiensis complex (Dumontiaceae, Rhodophyta): Molecular phylogeny, taxonomic characterization, and the proposal of new speciesPublication . Gabriel, Daniela; Draisma, Stefano; Sauvage, Thomas; Schmidt, William; Fredericq, SuzanneABSTRACT: The genus Gibsmithia was erected on the basis of G. hawaiiensis Doty 1963 from the Hawaiian archipelago to accommodate a species of red algae in the Dumontiaceae consisting of clusters of gelatinous lobes growing from a cartilaginous stalk. Three additional species were subsequently described from Australia, i.e. G. dotyi Kraft & R.W. Ricker 1984, G. larkumii Kraft 1986 and G. womersleyi Kraft & Ricker ex Kraft 1986. Records of Gibsmithia have been reported from different localities throughout the Indian Ocean and the central and western Pacific, with G. hawaiiensis acknowledged as having the widest geographic distribution. Gibsmithia hawaiiensis can be easily distinguished from the other species in the genus by the presence of abundantcortical filaments extending the frond's surface giving the specimens a furry appearance. Based on new subtidal collections and existing herbarium specimens, a study was conducted on the genetic diversity of specimens identified as G. hawaiiensis. The three genetic markers employed (COI, rbcL and UPA) revealed the existence of a species-complex comprising two major lineages, with genetically distinct species. The Gibsmithia hawaiiensis complex exhibits high genetic diversity in the Indo-Malay region, with one lineage distributed throughout the E Indian Ocean and the W Pacific, and a widespread second lineage collected from East Africa to French Polynesia. In contrast, low genetic diversity characterizes members from isolated regions as the Hawaiian archipelago and the semi-closed Red Sea. The high divergence associated with poor resolution observed in geographically widespread lineages obscures species boundaries. The generitype and two new species forming the Gibsmithia hawaiiensis complex can be distinguished on the basis of anatomical characters that were previously regarded as morphological plasticity within G. hawaiiensis. Additional studies are underway to assess the large-scale phylogenetic and biogeographic patterns in Gibsmithia.