Revision of Kadua (Rubiaceae) in the Marquesas Islands, French Polynesia, with description of the new species K. lichtlei

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
Until recently the Marquesas Islands were relatively poorly explored botanically. Prior to initiation of the Flore de la Polynésie française project under the auspices of Jacques Florence at IRD (formerly ORSTOM) no species of Rubiaceae belonging to tribe Spermacoceae were known from these islands (Brown 1935). Collecting there intensi-fied greatly with the onset of this project, and Florence and collaborators discovered two distinctive woody species of Kadua Cham. & Schltdl. One additional related species was discovered during the collecting phase of the current Vascular Flora of the Marquesas Islands project under the direction of David H. Lorence and Warren L. Wagner (Wagner and Lorence 1997; see website at http://botany.si.edu/pacificislandbiodiversity/marquesasflora/index.htm). These new taxa were published as Hedyotis lucei, H. nukuhivensis, and H. tahuatensis by Florence and Lorence (2000). Additional field work in [2003][2004] revealed the presence of yet another species on Ua Huka apparently not closely related to the other three which is described below.
Generic delimitations in Hedyotis L. and related genera in Hedyotidinae have not been fully resolved, although recent morphological and molecular studies suggest that Hedyotis s. str. is an Old World genus ranging from southeastern Asia to the Caroline Islands of Micronesia and with two widespread species ranging into western Polynesia (Church 2003;Terrell and Robinson 2003;Kårehed et al. 2008;Groeninckx et al. 2009). Virtually all the Polynesian species, the majority Hawaiian, were formerly placed in Hedyotis (Fosberg 1943;Wagner et al. 1990). However, results from a recent study of Hawaiian species of Kadua, focusing on capsule and seed morphology, revealed that these characters of Hawaiian and certain South Pacific species are distinct from other Asian and western Pacific species of Hedyotis, and consequently they have been transferred to the genus Kadua (Terrell et al. 2005). Kadua now comprises some 30 species including this new species and K. haupuensis Lorence & W. L. Wagner, a new species recently described from Kaua`i (Lorence et al. 2010).
Based on their salverform, fleshy corollas with appendaged lobes and non-diplophragmous capsules (i.e., that do not separate into paired cocci after dehiscing), the three Marquesan species formerly placed in the genus Hedyotis (Florence & Lorence 2000) have been transferred to the genus Kadua by Terrell et al. (2005) (Motley 2003).
Distribution. This new species is known only from Ua Huka, Marquesas Islands, where it is apparently restricted to the Hokatu cliff zone above Hane village.
Ecology. Rare and localized, this new species occurs in mixed wet shrubland and herbland growing on basalt cliffs and rock outcrops above wet forest of Hibiscus tiliaceus L., Pandanus tectorius Parkinson, and Freycinetia impavida (Gaudich. ex Hombr.) B.C. Stone. Other associates include species of Bidens, Boehmeria, Maytenus, Peperomia, Alyxia, Morinda, Phyllanthus, Miscanthus, Macropiper, Xylosma, and diverse pteridophytes. It was collected in flower in December and June (in bud), and in fruit in June and December (old fruit with a few seeds). Etymology. We are pleased to name this new species in honor of Mr. Léon Lichtle, Mayor of Ua Huka, for his generous help and logistic support when we conducted field work on the island and also in recognition of his strong support for conserving the island's native flora and fauna.
Distribution. Marquesas Islands, Fatu Hiva where known only from a single small population on the summit ridge between Tekou and Touaouoho peaks.
Ecology. This new species was collected at 915-1000 m elevation on a steep, precipitous ridge crest in wet shrubland with species of Alsophila, Freycinetia, and Histiopteris.
Etymology. The specific epithet honors its discoverer and first collector, Mr. Jean-Pierre Luce, an amateur naturalist, in recognition of his efforts to explore the most rugged mountainous zones of the Marquesas and thus increase our knowledge of their flora and vegetation.
Conservation status. The suitable habitat for Kadua lucei on Fatu Hiva (ca. 85 km 2 ) is indicated as an endangered environment, threatened by feral animals and invasive plants, reducing the extent of the forest. Estimated population size is about 3-4 individuals. Following the criteria and categories of IUCN (2001) Kadua lucei is assigned a preliminary Red List 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. Discussion. This species is apparently related to Kadua tahuatensis from which it differs by its larger inflorescence reaching 8-9 cm long and 6 cm wide, more numerous flowers, about 30 per inflorescence, and larger white corollas with a longer purple-tinged tube 22-26 mm long. Although mature fruits of K. lucei are not known, old fruits are smaller than those of K. nukuhivensis and K. tahuatensis.
Distribution. Marquesas Islands, Nuku Hiva, where known only from the island's central mountain crest, on the leeward side of the Terre Déserte in the upper Tapuaehu Valley, between 1000 and 1065 m elevation.
Ecology. This species occurs in wet forest with species of Hernandia, Ilex, Metrosideros, and Weinmannia in the canopy and the understory with species of Cyrtandra, Melicope, and Psychotria. Numerous pteridophytes occur terrestrially and as epiphytes. Kadua nukuhivensis also occurs in shrubland on ridge crests with species of Alsophila, Bidens, Dicranopteris, Elaphoglossum, Freycinetia, Pennisetum, and Styphelia. Etymology. The specific epithet refers to the only known island of occurrence for this species.
Etymology. The specific epithet refers to the only known island of occurrence for this species.
Distribution. Marquesas Islands, Tahuata, known only from the island's summit crest and high southeastern slopes between 780 and 835 m elevation.
Ecology. Occurs in wet montane forest and shrubland with species of Alsophila, Cheirodendron, Crossostylis, Hibiscus, Metrosideros, Reynoldsia, Weinmannia, and pteridophytes including Asplenium, Blechnum, Elaphoglossum, Lycopodiella and Nephrolepis, Conservation status. The suitable habitat for Kadua tahuatensis on Tahuata (c. 61 km 2 ) is indicated as an endangered environment, threatened by feral animals and invasive plants, reducing the extent of the forest. This species is extremely rare, with only five plants known from two localities. 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. Discussion. Morphologically Kadua tahuatensis closely resembles K. nukuhivensis, and molecular evidence places these two as sister species in the same clade as K. rapensis F. Br. and K. romanzoffiensis Cham. & Schltdl. within the larger clade of Hawaiian and French Polynesian species (Motley 2003).