Revision of Coprosma (Rubiaceae, tribe Anthospermeae) in the Marquesas Islands

Abstract During the preparation of the Vascular Flora of the Marquesas Islands three new species of Coprosma (Rubiaceae, tribe Anthospermeae) have come to light and are described herein: Coprosma fatuhivaensis W. L. Wagner & Lorence, Coprosma meyeri W. L. Wagner & Lorence, and Coprosma temetiuensis W. L. Wagner & Lorence. Descriptions, illustrations, conservation status, and specimen citations are provided. Amended descriptions of three previously described Marquesan Coprosma species are also provided as well as a key to the species, four of which fall into the Critically Endangered (CR) and two into the Endangered (EN) category. With the description of these the new species, Coprosma becomes the sixth largest lineage in the Marquesas Islands with six species after Psychotria (one lineage which has 9 spp.), Cyrtandra (8 spp.), Bidens (8 spp.), Melicope (7 spp.), and Ixora (7 spp.).


Introduction
Coprosma J.R. Forst. & G. Forst. is a genus of about 110 species, unusual in most species being dioecious and wind-pollinated. The genus is widely distributed on Pacific islands with a primary center of diversity in New Zealand (ca. 50 spp.), but with secondary centers of diversity the Hawaiian Islands (13 spp.), New Guinea (11 spp.), and Australia (8 spp.). The remainder are scattered over a wide area of the Pacific Basin, extending to southeastern Polynesia and the Juan Fernández Islands. There are 16 species of Coprosma in Polynesia, with six species endemic to the Marquesas Islands, four in the Society Islands, three in the Australs, two in Samoa, and one each in the Tuamotu Islands, Pitcairn Island, and Cook Islands. Oliver (1935) divided the genus into seven groups, most of which were subdivided into smaller groups of presumably closely related species. He placed all southeastern Polynesia species then known into his Coprosma pyrifolia group characterized by relatively large leaves that are usually obovate to ovate and finely reticulate, triangular stipules, which are entire to denticulate, male flowers in small clusters with a calyx present, and female flowers 3 per cluster, the calyx lobes as long as or shorter than the tube. He hypothesized that this group was related to similar species in New Zealand. Florence (1986) in a paper describing two new Marquesan species (C. nephelephila Florence and C. reticulata Florence) allied them and the one other Marquesan species then known [C. esulcata (F. Br.) Fosberg] with the orange-fruited Hawaiian species. Heads (1996) supported Florence's hypothesis by placing the Marquesan species in a group with the Hawaiian species, rather than the C. pyrifolia group where all of the other southeastern Polynesian species were placed. No comprehensive study of relationships has been made, but a recent molecular study of Tribe Anthospermeae (Anderson et al. 2001), in which 6 of 16 of the taxonomic groups recognized by Heads (1996) were sampled, indicates an apparent Australian origin of Coprosma and possible independent colonization of Fiji and Hawaiian Islands from New Zealand. The two subgenera of Coprosma recognized by Heads (1996) were not supported. No Polynesian species were included in the sparse sampling of the genus leaving the relationships and biogeography of the genus in the Pacific completely open. The species in the following taxonomic section of this paper are arranged alphabetically. Brown (1935) described the first species of Coprosma discovered in the Marquesas Islands in his Rubiaceae treatment for the Flora of Southeastern Polynesia, but mistakenly placed it in the genus Psychotria as P. esulcata F. Br. Fosberg (1939) in his revision of Marquesan Psychotria maintained it as a species of Psychotria; however, he later (Fosberg 1956) realized it was actually a poorly understood species of Coprosma and transferred to its proper place as C. esulcata (F. Br.) Fosberg. It remained the sole Marquesan member of the genus until the Flore de la Polynésie française project under the auspices of Jacques Florence at IRD (formerly ORSTOM) was initiated. Collecting in the Marquesas Islands intensified greatly with the initiation of this project and Florence (1986) discovered two additional species of Coprosma (C. nephelephila and C. reticulata). During the collecting expeditions for the current Vascular Flora of the Marquesas Islands project under the direction of David H. Lorence and Warren L. Wagner (Wagner & Lorence 1997) three additional species were discovered, bringing the total to six species. This paper, a generic revision for the Marquesas Islands with descriptions of new taxa, represents a precursor to the latter project.

Conservation status
The Marquesan species of Coprosma are distributed with a typical higher diversity on the older and larger islands. Three species occur on Nuku Hiva (C. esulcata, C. nephelephila and C. reticulata), one on Ua Pou (C. esulcata), two on Hiva Oa (C. feaniana and C. temetiuensis), and one on Fatu Hiva (C. fatuhivaensis). To date only 36 total collections of Coprosma have been made of the Marquesan species, which gives an indication of how uncommon these species are. Two of the species, C. esulcata and C. reticulata, constitute the bulk (26) of the collections. Both of these species occur as scattered individuals in appropriate habitats or are occasionally locally common. The other four species are known from only a few collections. When evaluated using the IUCN criteria for endangerment (IUCN 2001), four of the Marquesan Coprosma species of (C. fatuhivaensis, C. meyeri C. nephelephila, and C. temetiuensis ) fall into the Critically Endangered (CR) category, which designates species facing the highest risk of extinction in the wild. Marquesan species of Coprosma meet the IUCN criteria by having known ranges less than 100 km 2 , an area of occupancy of less than 10 km 2 , continuing decline in the quality of habitat, and a populations size less than 50 mature individuals. Coprosma esulcata and C. reticulata are considered Endangered (EN): B1, B2b (i-iii): B1 extent of occurrence <5,000 km²; B2: total area of occupancy less than 500 km² (c. 75 km²); B2b (i-iii), habitat continuing decline inferred in (i) extent of occurrence, (ii) areas of occupancy, and area, (iii) extent and/or quality of habitat. Further details are given under each species.

Key to species of
Distribution: Marquesas Islands, scattered to locally common on Ua Pou and a single collection known from Nuku Hiva.
Ecology. This species is known from 770 to 920 m elevations on steep slopes or ridges in cloud-shrouded shrubland and wet forest dominated by Conservation status. Following the criteria and categories of IUCN (2001) it is assigned a preliminary status of Endangered (EN): B1, B2b (i-iii): B1 extent of occurrence <5,000 km²; B2: total area of occupancy less than 500 km² (c. 50 km²); B2b (i-iii), habitat continuing decline inferred in (i) extent of occurrence, (ii) areas of occupancy, and area, (iii) extent and/or quality of habitat. The suitable habitat for C. esulcata on Nuku Hiva (c. 340 km²) and Ua Pou (c. 105 km²) is indicated as an endangered environment, threatened by human activity (deforestation and fire), feral animals, and invasive plants, reducing the extent of the forest. Description. Tree ca. 7 m tall; young stems short-pilose. Leaves opposite, thinly coriaceous, blades 5.3-6.7 × 0.9-1.8 cm, narrowly elliptic, pinnately veined with 8-9 pairs of secondary veins, higher level venation conspicuously reticulate, both surfaces glabrous, domatia minute, usually subcircular, located along midrib near juncture of secondary veins, apex acute, base attenuate; petioles 0.7-1.1 cm long; stipules ca. 2-2.5 mm long, connate 4/5 of length, both surfaces glabrate, margins weakly ciliate and dentate with a larger and sometimes also a few small colleters, the colleters often with a small tufts of a few hairs. Inflorescences axillary, subsessile, with 3 flowers, these 5-6-merous. Flowers: male flowers unknown; female flowers with peduncles to 4.2 mm long, calyx short-tubular, ca. 0.5-0.6 mm long, the tube ca. 0.1-0.2 mm long, the lobes triangular, 0.3-0.4 mm long, corolla narrowly funnelform, the tube 2 mm long, the lobes 1.2-1.3 mm long. Fruit and pyrenes unknown.
Etymology. The specific epithet refers to the only known island of occurrence for this species.
Distribution. This new species is known only from a single collection at the type locality in the southern summit region at 870 m on Fatu Hiva, Marquesas Islands.
Distribution. Coprosma meyeri is known only from the type locality at ca. 1090-1113 m elevation in the Feani area along the trail to Hanamenu on the summit crest of Hiva Oa, Marquesas Islands.
Etymology. The specific epithet honors Dr. Jean-Yves Meyer, conservation biologist at the Délégation à la Recherche, Polynésie française, in recognition of his untiring efforts to explore and conserve the biodiversity of French Polynesia.
Distribution. Known only from the Toovii area of Nuku Hiva, Marquesas Islands. Ecology. Coprosma nephelephila is known from 970 to 1100 m elevation, scattered in montane cloud forests dominated by Metrosideros and Weinmannia associated with with species of Alsophila, Crossostylis, and Ilex.
Distribution. Known only from the Toovii area of Nuku Hiva, Marquesas Islands, at elevations from 800 to 1100 m.
Etymology. The specific epithet refers to the distinctive reticulate network of tertiary veins.
Conservation status. Based on the IUCN criteria and categories this species is assigned a preliminary Red List status of Endangered (EN): B1, B2b (i-iii): B1 extent of occurrence <5,000 km²; B2: total area of occupancy less than 500 km² (c. 50 km²); B2b (i-iii), habitat continuing decline inferred in (i) extent of occurrence, (ii) areas of occupancy, and area, (iii) extent and/or quality of habitat. The suitable habitat for C. reticulata on Nuku Hiva (c. 340 km²) is indicated as an endangered environment, threatened by human activity (deforestation and fire), feral animals, and invasive plants, reducing the extent of the forest. The population size for this species is unknown, but based on available herbarium specimens (14)  Description. Shrubs 4-6 m tall; young stems short-pilose. Leaves opposite, thinly coriaceous, blades 5.1-9.1 × 2.1-3.6 cm, elliptic, pinnately veined with 8-9 pairs of  veins, higher level venation conspicuously reticulate, both surfaces glabrous, domatia small, usually somewhat elongate, located along midrib near juncture of secondary veins, apex acuminate, base cuneate; petioles 0.3-0.8 cm long; stipules ca. 1.5-3 mm long, connate 4/ 5 of length, both surfaces glabrous, margins glabrous and dentate with a few small colleters, apex obtuse to a conspicuous appendage. Inflorescences axillary with 3(-7) flowers, with 1-3 nodes, the uppermost with a 3-flowered cymule, the others with usually only 1-2 flowers developing on each, these 5-merous, the peduncles 0-4 mm long, finely short-pilose. Flowers: male flowers unknown; female flowers with calyx short-tubular, 0.25-0.3 mm long, the teeth ca. 0.2 mm long, glabrous, corolla narrowly funnelform, the tube 0.3 mm long, the lobes 2.2-2.5 mm long, glabrous, the styles 5.5-7 mm long. Young fruits sparsely pilose, fruits and pyrenes otherwise unknown.
Distribution. Known only from areas the vicinity of Mt. Temetiu, the highest peak on Hiva Oa, Marquesas Islands.
Etymology. The specific epithet refers to the only known locality for this species. Conservation status. This species is extremely rare, with only two plants known from this locality. Following the criteria and categories of IUCN (2001) it is assigned a preliminary status of Critically Endangered (CR): B2a, B2b (i-iii); D: B2: total area of occupancy less than 10 km 2 (ca. 5 km 2 ). B2a, a single population known; b (i-iii), habitat continuing decline inferred; D, population estimated to number fewer than 250 individuals. The suitable habitat for Coprosma temetiuensis on Hiva Oa (c. 315 km 2 ) is indicated as an endangered environment, threatened by human activities (deforestation and fire), feral animals, and invasive plants, reducing the extent of the forest.