A nomenclator of Pacific oceanic island Phyllanthus (Phyllanthaceae), including Glochidion

Abstract Recent molecular phylogenetic studies and reevaluation of morphological characters have led to the inclusion of Glochidion within a broader delimitation of Phyllanthus. It is necessary for preparation of the Vascular Flora of the Marquesas Islands to make new combinations for the Marquesan species. We also provide the relevant combinations and listing of all of the currently accepted species of Phyllanthus on Pacific oceanic islands for a total of 69 native species in oceanic Pacific islands. Glochidion tooviianum J. Florenceis here placed into synonymy of Phyllanthus marchionicus (F. Br.) W. L. Wagner & Lorence based on new assessment of recently collected specimens from Nuku Hiva. Glochidion excorticans Fosberg var. calvum Fosberg is placed into synonomy of Phyllanthus ponapense (Hosokawa) W. L. Wagner & Lorenceand Glochidion puberulum Hosokawa and Glochidion excorticans Fosberg are placed in synonymy of Phyllanthus senyavinianus (Glassman)W. L. Wagner & Lorence based on new study of all Micronesian specimens available to us. No infraspecific taxa are recognized within Phyllanthus pacificus of the Marquesas Islands. Species already with valid names in Phyllanthus are also listed for completeness and convenience. Brief distributional comments are given for each species. We propose new names for species for which a new combination is not possible: Phyllanthus florencei W. L. Wagner & Lorence, nom. nov., Phyllanthus mariannensis W.L. Wagner & Lorence, nom. nov., Phyllanthus otobedii W. L. Wagner & Lorence, Phyllanthus raiateaensis W. L. Wagner & Lorence, Phyllanthus st-johnii W. L. Wagner & Lorence, nom. nov., and Phyllanthus vitilevuensis W.L. Wagner & Lorence, nom. nov. We provide information for four additional naturalized species within the region (Phyllanthus amarus, Phyllanthus debilis, Phyllanthus tenellus, and Phyllanthus urinaria). The name Glochidion ramiflorum widely applied to Pacific island populations is here considered to be a species further west in the Pacific with all of the oceanic species here referred to several regional species.


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Recent molecular phylogenetic studies have greatly advanced the understanding of relationships in the family Phyllanthaceae (a segregate from Euphorbiaceae s. l.) based on chloroplast and nuclear DNA sequence data (Wurdack et al. 2004;Samuel et al. 2005;Kathriarachchi et al. 2005Kathriarachchi et al. , 2006. Among the tribes in Phyllanthaceae , tribe Phyllantheae is the largest natural group and accounts for more than half of the 2000 species in the family Hoffmann et al. 2006). One of the most taxonomically difficult groups in the family is Phyllanthus L. and related genera, species of which have small unisexual flowers and an often confusingly similar habit in unrelated groups. Historically generic circumscriptions in Phyllantheae have undergone substantial fluctuation, and the definition of natural groups is still unclear in many parts of the tribe . The recent molecular studies of relationships within the family, with special emphasis on the large genus Phyllanthus, confirm paraphyly of Phyllanthus in its traditional circumscription with Breynia J. R. Forst. & G. Forst., Glochidion J. R. Forst. & G. Forst., Reverchonia A. Gray, and Sauropus Blume embedded within Phyllanthus. These results led the research groups working on Phyllanthaceae Kathriarachchi et al. 2006) to conclude that the embedded genera should be submerged into a broadened Phyllanthus rather than further generic segregation, which would create a series of highly technical genera distinguishable only by specialists. Distinguishing morphological characters among these five taxa are not clear-cut or comparable, and thus recognition of equivalent clades at generic level would exacerbate the problem of understanding the evolution of this large and widespread lineage . The enlarged Phyllanthus comprises nearly 1300 species with the inclusion of Breynia, Glochidion, Reverchonia, Phyllanthodendron Hemsl., and Sauropus. It is not surprising that the vast morphological diversity of Phyllanthus prior to adding the embedded taxa would readily accommodate them . Unfortunately, the broadening of Phyllanthus necessitates a considerable number of new combinations, but nevertheless this seems to be the best approach over the long term in the interest of developing a classification that facilitates understanding of the evolution and relationships in the overall group.
Our work has focused on the oceanic Pacific and specifically we are currently completing investigation of the flora of the Marquesas Islands as part of a collaboration between National Tropical Botanical Garden (NTBG), Smithsonian Institution (SI), and the Délégation à la Recherche, Papeete, Tahiti (French Polynesia). We do not believe it is wise to make only the necessary combinations for just the Marquesan species previously placed in Glochidion so we here provide a synopsis of all of the Pacific oceanic island species (Fiji and Caroline Islands eastward across the Pacific). We also include all of the species currently recognized within Phyllanthus for completeness. We have not made an exhaustive study of the taxonomy of these species, but accept for the most part previous taxonomic conclusions. The Pacific group of species is in serious need of comprehensive analysis as previous work has focused on localized areas with few excep-tions. Smith (1981) and Florence (1997) have made good regional taxonomic studies, but both point out problems that need a broader geographical perspective to solve. The Micronesian species are in particular need of comprehensive study and have received only partial treatments, either of part of the region (Hosokawa 1935) or more superficial descriptive work (Fosberg and Oliver 1991) without consideration of all species previously described. We have made some changes to the taxonomy of these species, but an in depth study is required to gain a more solid understanding of the diversity within Micronesia. Webster (1986) also made a partial study in the region, primarily of southwestern Pacific species, and Croizat (1943) contributed a useful analysis of several species. We have made extensive use of the Euphorbiaceae world checklist (Govaerts et al. 2000) in compiling the list presented here.   (Smith 1981).
Distribution. Endemic to the island of Eua, Tonga (Webster 1986) where it is only known from forest margins and exposed rocks, 300m, on the Liku Plateau. Distribution. Endemic to the Society Islands and known only from Tahiti at about 1000 m elevation on a ridge crest. Not collected since 1857 and presumed extinct (Florence 1997 Distribution. Endemic to Fiji and know only from coastal and slightly inland areas of southern Viti Levu from 50-100 m in dry or dense forest (Smith 1981 Distribution. Endemic to Pohnpei where it occurs from ca. 12 to 770 m elevation, most commonly in lowland wet forest and agroforest, but occasionally in summit cloud forest.

Phyllanthus anfractuosus
Note. This species is distinctive in having oblong-ovate to narrowly oblong-elliptic leaves and comparatively small flowers in umbel-like fascicles often borne on short, sometimes branched stalks or peduncles to 5 mm long, a densely puberulent pistil with a puberulent columnar style exserted for 1-1.5 mm beyond the calyx lobes, and relatively small, densely puberulent fruits. Pohnpei collections of this species have been identified as Glochidion ramiflorum or less commonly G. puberulum.  (Smith 1981), and also from Niue (Sykes 1970) from 0 to 1000 m elevation in dense or open forest, edges and forest-grassland transition, and on open slopes. These collections were previously referred to Glochidion ramiflorum, but were considered by Smith (1981) to be a separate species. He considered G. ramiflorum to be a species from New Guinea to New Hebrides. Distribution. Phyllanthus distichus is endemic to the Hawaiian islands where it is occasional to locally common in mesic forest, often on steep slopes or ridge tops, sometimes in dry shrubland at 60-950 m on the islands of Kaua`i, O`ahu, Moloka`i, Lana`i, West Maui, and rare on East Maui. A number of additional names have been applied to populations of P. distichus, but they were placed into synonymy by Wagner et al. (1990Wagner et al. ( , 1999 and are not repeated here. Note. This entity should be carefully evaluated in the context of an overall review of Phyllanthus in Micronesia. It may be conspecific with G. cleistanthoides, in which case we would adopt the latter name because the description applies most closely to this species and the holotype is available at B. Note. Precise locality uncertain, known only from a single collection possibly made in the Marquesas Islands (Nuku Hiva) by Jardin in the 19 th century (Florence 1997 [Fosberg et al. 1979;Wagner et al. unpubl.]), Yap (Yap Island), and Chuuk (Moen Island, also Tol, Udot, Uman, Dublon, Fano, Fanurmot [Fosberg et al. 1979;Wagner et al. unpubl.]). On Palau it is restricted to limestone substrate from near sea level to about 200 m elevation in coastal forest with speices of Bruguiera, Heretiera, Semecarpus, Osmoxylon, and Phyllanthus, and in lowland evergreen forest with Horsfieldia and Phyllanthus and agroforest. On Chuuk it occurs near sea level (3 m) in coastal forest interspersed with mangroves and on slopes of unknown elevation in agroforest and secondary vegetation. On Yap it occurs from near sea level at the edge of mangrove vegetation and on slopes up to 40 m with secondary vegetation.

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Note. This glabrous species is characterized by female flowers with a small, depressed-globose pistil 1-1.5 mm long with a very short 10-11-fid stylar column 0.5 mm long. Certain collections from Yap have been identified as Glochidion cf. ramiflorum, and certain collections from Palau have been identified as Glochidion palauense. Note. This glabrous species is characterized by female flowers with relatively large calyx lobes enclosing the short, depressed-ovoid pistil 1.5 mm long with a very short style column and flat 5-6-sulcate or -lobed stigmatic region. In male flowers the staminal column is composed of 5 connate stamens (versus 3-4 in other Micronesian species).  (Guam) where it occurs on limestone and basaltic soils in old fields and grasslands and disturbed native and secondary vegetation at ca. 60-150 m elevation.

Phyllanthus manono
Note. The ovate leaves with short acuminate to rounded apices and glabrous columnar style 1.5-2 mm long exserted beyond the calyx lobes are characteristic of this species. Collections from Caroline Islands (Pohnpei) previously identified as this species are here considered to represent P. senyavinianus.  Distribution. Endemic to the Mariana Islands (Guam, Aguijan, Agrihan, Alamagan, Anathan, Asuncion, Guguan, Maug, Pagan, Rota, Saipan, Sarigan, Tinian) and the Caroline Islands (only on Ulithi Atoll). On Guam it is common on limestone cliffs and terraces. Distribution. Endemic to Palau on Babeldaob, Anguar, Ngerechong, Ulebsechel, Ulong, and the Rock Islands (Koror, Ngerukeuid, Ngeruktabel). On Babeldaob this species occurs on basaltic soils in evergreen wet forest and savannas at about 100 m elevation. On the Rock Islands it occurs on limestone substrate near sea level (2-5 m elevation) in evergreen coastal forest and cliff vegetation. This glabrous species is distinguished by its female flowers with a conical-columnar pistil 3 mm long with a cylindrical style and shortly 6-7-lobed stigma.

Phyllanthus melvilliorum (Airy
Etymology. We are pleased to name this species for Mr. Demei O. Otobed, president of the board of directors of the Belau National Museum, who has done so much to advance the study and conservation of Palau's biodiversity.
Note. Some Palau collections of this species were identified as Glochidion macrosepalum. Distribution. Endemic to Pohnpei, this species occurs from lowland wet forest up into montane cloud forest on summits from 20 to 732 m elevation.

Phyllanthus pacificus
Note. This species is characterized by its female flowers with a short, glabrous, depressed-globose ovary 0.5 mm long and glabrous columnar style 1-1.5 mm long with a 6-7-dentate stigma. Some collections of Phyllanthus ponapense were previously identified as Glochidion marianum or G. ramiflorum. Note. The sheet (BISH-142814) was considered by Florence (1997) to not be part of the type because it was pubescent vs. glabrous as in the holotype. The full variation of P. raiateaensis is not well understood, but Florence accepted both specimens as this species. Without further supporting information that this really represents a mixed collection it seems best to accept the second sheet as an isotype. However, even if the second sheet is not accepted as an isotype, the first sheet is clearly the holotype as it was explicitly stated as such and shown in a figure in the original publication.

Phyllanthus raiateaensis
Distribution. Endemic to the Society Island of Raiatea where it is known from the Temehani plateau region at 435-750 m, occurring in wet forest with Metrosideros, Weinmannia, and Myrsine and in open marshland with Metrosideros and species of Cyperaceae (Florence 1997).   Bull. 226: 9. 1963, nom. illeg., non Yamamoto (1933. Glochidion longipes P.T.Li, Acta Phytotax. Sin. 20:117. 1982 Savai`i, Upolu, Tutuila, Aunu`u, Ofu, Olosega, and Ta`u) at 60-1000 m disturbed forest, secondary forest, and pastures (Whistler 1980). Note. Even though the varietal name was published under an illegitimate species it is legitimate under Art. 55.2 of the ICBN and is available for use at the specific level. These Samoan collections were previously referred to Glochidion ramiflorum, but were considered by Smith (1981) (2 m) to 770 m in primary and secondary lowland and montane wet forest and summit cloud forest. On Moen it occurs in lowland areas among mangrove swamps near sea level and on slopes and ridges where said to be common in agroforest and secondary forest. Habitat is unknown on the other islands of Chuuk.

Phyllanthus rupiinsularis
Note. This species is characterized by its variably pubescent stems and densely hirtellous pistil and capsules. Collections from Chuuk resemble P. senyavinianus in having a densely hirtellous ovary and style, but the pistil is comparatively shorter and only as long as the calyx lobes, and the leaves are narrowly ovate-oblong. These collections from Chuuk were previously identified as Glochidion puberulum and are here tentatively included under P. senyavinianus, but may represent an undescribed species. Chuuk collections of P. kanehirae differ in having female flowers with a glabrous pistil nearly twice as long as the calyx lobes. Some of these collections were previously identified as G. puberulum. Certain Pohnpei collections of P. senyavinianus were previously identified as G. ramiflorum or G. marianum.
Note. Smith (1981) treated P. virgatus as native in Asia, but likely naturalized in the Pacific as did Florence (1997). Webster (1986) found a number of morphological features (smaller seeds, short fruiting pedicels, smooth to slightly roughened ovaries, and an irregularly dissected disk) that distinguish the Pacific island populations from the mainland Asian ones, and thus the Asia plants are most likely a different species, P. simplex Retz. Considering these differences the Pacific island P. virgatus is likely a native and not found outside of Pacific islands. A complex set of considerations would be involved to make a proper lectotypification for this species. A. C. Smith (1981, p. 464) suggested that one of two collections at BM (Banks & Solander s.n.) be selected by a specialist as the lectotype. Webster (1986) incorrectly considered Smith's comments to be a lectotypification, and Nicolson and Fosberg (2004) summarized the Cook voyage materials available, including Foster collections. They thought it inappropriate to select the Banks and Solander collection as the lectotype while also pointing out that a specialist needs to make the selection because the original material could represent a mixture of this species or P. simplex Retz. or P. maderaspatensis L.  (Smith 1981). ( Distribution. Caroline Islands, Pohnpei, known only from the type without specific locality.

Phyllanthus websteri
Note. A glabrous species to date know only from the type collection which has only pistillate flowers. The glabrous pistil is cylindrical with a columnar style 2-2.5 mm long exserted well beyond the calyx lobes. It most closely resembles and may be conspecific with P. ponapense. This entity should be carefully evaluated in the context of an overall review of Phyllanthus in Micronesia. Distribution. Presumably native to the Neotropics, but now naturalized across tropical regions of the world; in the Pacific on Fiji, Austral, Cook, Gambier, Marquesas, Samoa, Society, Tuamotu Islands, and widespread in Micronesia (Carolines, Gilberts, Marshalls, Marianas, Nauru, and Wake) at 0-600 m elevation. Distribution. Native to southern Asia and now naturalized pantropically; it is naturalized across the Pacific and currently known from Fiji, Austral Islands (Rurutu), Marquesas Islands (Fatu Hiva), Society Islands (Huahine, Moorea, Raiatea, Tahaa, and Tahiti), Caroline Islands and Maraiana (Guam) Islands in Micronesia, at 0-1200 m.