Saribus Resurrected
Total Page：16
File Type：pdf, Size：1020Kb
PALM S Bacon & Baker: Saribus Vol. 55(3) 2011 CHRISTINE D. B ACON Department of Biology, Colorado State University, Fort Collins, CO 80523 USA Saribus [email protected] Resurrected AND WILLIAM J. B AKER Royal Botanic Gardens, Kew, Richmond, Surrey, TW9 3AB, UK Recent analysis of molecular data uncovered the startling fact that Livistona , as currently recognized, is not a natural, coherent genus and that eight of its species, including the widely cultivated Livistona rotundifolia , along with the rare Pritchardiopsis jeanneneyi constitute a distinct genus, for which the earliest name is Saribus . The palm tribe Trachycarpeae contains some Our primary goal was to test the delimitation of the most widely cultivated fan palms, such of the genera of Trachycarpeae by determining as Livistona chinensis , Pritchardia pacifica , whether or not they constitute natural Trachycarpus fortunei and Washingtonia filifera . evolutionary units containing all descendants The group is among the most widespread of all of a common ancestor (monophyletic groups). palm tribes and its species are conspicuous Our molecular data indicated that the majority components of many different vegetation of genera were indeed monophyletic. Livistona , types, from deserts and pinelands to tropical however, was not found to be monophyletic, rainforests. but was divided among two different groups Despite more than a decade of DNA-based that were not each other’s closest relative (Fig. phylogenetic research aimed at revealing 1). One group comprised three Livistona species evolutionary relationships of palms (e.g. (L. merrillii , L. rotundifolia and L. woodfordii ) Asmussen et al. 2006, Baker et al. 2009), the and two samples of the monotypic Trachycarpeae remains one of the most Pritchardiopsis jeanneneyi . The second group significant areas of phylogenetic ambiguity included 19 Livistona species from eastern Asia, within the family due to poor resolution south-east Asia, Australia and Africa. The among genera and low support for grouping of the three Livistona species and relationships. To address this problem, a Pritchardiopsis was highly supported and was focused tribal-level analysis using DNA more closely related to Pholidocarpus , Licuala evidence has been conducted recently, based and Johannesteijsmannia than to the remaining on dense sampling across 113 species and six species of Livistona . Thus, to render all different regions of the genome (Bacon et al., Trachycarpeae genera monophyletic, this in review). This new phylogenetic framework group requires recognition at the genus level. has provided the best estimate of relationships A generic name, Saribus (Blume 1838) typified among the genera of Trachycarpeae available on Saribus rotundifolius (Lam.) Blume (syn. to date and has yielded some surprising Livistona rotundifolia (Lam.) Mart.), is already taxonomic and biogeographic insights. available for this group. It takes priority over PALMS 55(3): 109 –116 109 PALM S Bacon & Baker: Saribus Vol. 55(3) 2011 1. Phylogeny of relationships between Saribus and the remaining genera of subtribe Livistoninae (tribe Trachycarpeae) based on Bacon et al. (in review). Numbers on branches are parsimony support values for each node on the tree. The asterisk indicates support less than 50%. Saribus is well-supported (100%) and separate from Livistona . the other generic name in the group, boninensis, L. chinensis, L. endauensis, L. exigua, Pritchardiopsis (Beccari 1910), which must be L. halongensis, L. jenkinsiana, L. saribus, L. placed as a synonym of Saribus because of its speciosa and L. tahanensis ), in addition to the later publication date. known disjunction in Arabia and the Horn of Saribus includes a Philippines endemic species Africa ( L. carinensis ). (S. merrillii ), a group of Papuasian species ( S. The occurrence of Livistona carinensis in brevifolius, S. chocolatinus, S. papuanus, S. Djibouti, northern Somalia, and southern rotundifolius, S. surru, S. tothur and S. woodfordii ), Yemen, so distant from remaining species of an outlier species in New Caledonia ( S. the genus, has fascinated many palm jeanneneyi ) and one species widespread in biologists. First recognized as a species of Malesia ( S. rotundifolius ) (Fig. 2). The removal Hyphaene , it was placed by Burret in the of Saribus reveals a new disjunction in the monotypic genus Wissmannia in 1943. distribution of true Livistona between Australia However, on grounds of close morphological and southern New Guinea ( L. alfredii, L. and anatomical similarities, Dransfield and australis, L. benthamii, L. concinna, L. decora, L. Uhl (1983) reduced W. carinensis into drudei, L. eastonii, L. fulva, L. humilis, L. inermis, synonymy with Livistona (see also Tomlinson L. lanuginosa, L. lorophylla, L. mariae, L. muelleri, 1961a, Monod 1955). The placement of L. L. nasmophila, L. nitida, L. rigida and L. victoriae ) carinensis within Livistona sensu stricto is and tropical Asia west of Wallace’s Line ( L. strongly supported by our DNA data. Our 110 PALM S Bacon & Baker: Saribus Vol. 55(3) 2011 biogeographical results are consistent with green, blue, purple, brown or black (Dowe Dransfield and Uhl’s (1983) hypothesis that 2009, Dransfield et al. 2008). It should be the distribution of Livistona was once much noted that this group had already been more widespread during the time of the highlighted by Dowe (2009) as a distinctive northern boreotropical forests (Miocene; about element within Livistona in its former sense. 5–24 million years ago) and that, due to Because of these clear, consistent characters, we geological and climate changes, L. carinensis have been able to place several species in became isolated in the African-Arabian region Saribus that we were not able to sample for in a relict forest fragment. In our phylogenetic our phylogenetic research. analysis, L. carinensis is resolved on a long From an anatomical perspective, Saribus and branch as sister to all the remaining Livistona the rest of the Livistoninae excluding Livistona species, which suggests that there have been have intercostal cells of the adaxial epidermis high levels of extinction within this lineage. that are differentiated into long and short cells Nevertheless, there is no current phylogenetic within the same cell file. Livistona has adaxial justification for recognizing Wissmannia, and epidermal cells uniformly of the long cell type, given its high morphological similarity to like all genera of Trachycarpeae outside of Livistona , it is most appropriate to retain it Livistoninae (Tomlinson 1961b, Tomlinson et within the revised circumscription of this al. 2010). A similar character distribution genus. occurs for the presence of fibers that are Saribus is readily distinguished from Livistona associated with surface layers and also depart in the field, in cultivation and in the from the sheath of transverse veins of the herbarium. The morphological characters that lamina ramifying in the mesophyll (Tomlinson enable identification of Saribus include 1961b, Tomlinson et al., 2011). These character trifurcate inflorescences, consisting of three states, though not unique to Saribus , further main axes (sometimes two) that join at their distinguish Saribus from Livistona . base within a single prophyll (Fig. 3), whereas The reduction of the monotypic Pritchardopsis Livistona produces inflorescences comprising a into synonymy as Saribus jeanneneyi is a single main axis only (Dowe 2009). Saribus has notable outcome of this research, given the orange, orange-brown, or red mature fruit rarity and conservation significance of this color (Fig. 4), whereas the fruits of Livistona are species, which persists as one adult and a few 2. The global distribution of Livistona and Saribus . 111 PALM S Bacon & Baker: Saribus Vol. 55(3) 2011 juveniles in the far south of New Caledonia. Taxonomic treatment of Saribus This taxonomic change is strongly supported Saribus Blume, Rumphia 2: 48. 1838. by both the molecular and morphological data Lectotype: S. rotundifolius (Lam.) Blume described above. Saribus jeanneneyi deviates (Corypha rotundifolia Lam.) slightly in some respects from other members of the genus. Its fruit are reported to be Pritchardiopsis Becc., Webbia 3: 131. 1910. purplish (Hodel & Pintaud 1998), although a synon. nov . Type: P. jeanneneyi Becc. near-ripe fruit figured in this reference is in Distribution: Philippines, Borneo (Banggi fact yellow-orange. The fruit are also large (ca. Island only), Sulawesi, Moluccas, New Guinea, 4 cm diam.; Hodel & Pintaud 1998) with seeds Solomon Islands, New Caledonia. surrounded by a keeled, woody endocarp (Dransfield et al. 2008). However, fruits of Saribus brevifolius (Dowe & Mogea) C.D. similar or larger size are found in some species Bacon & W.J. Baker, comb. nov. Livistona of Saribus (S. surru , S . tothur ) and at least one brevifolia Dowe & Mogea, Palms 48: 201. other has an equally woody, thickened 2004. Type: Indonesia, Papua, Raja Ampat endocarp ( S. papuanus ; Fig. 5). The loss of Islands, West Waigeo, Kawe Is., Nov. 2002, charismatic genera through nomenclatural Mogea et al. 8171 (holotype BO; isotypes K, change can be controversial, but it in no way L, MAN, NY). reduces the conservation importance of this Distribution: New Guinea (Raja Ampat Islands critically endangered New Caledonian only). endemic. In fact, by knowing its evolutionary relationships more clearly, we may be better Saribus chocolatinus (Dowe) C.D. Bacon & placed to understand its biology and to make W.J. Baker,