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Aims Analyse the controversial relationship existing between wood density, precipitation, temperature and aridity, and its importance in shaping forest communities facing drought. Location New Caledonia (SW Pacific). Methods We sampled wood density in 1580 trees belonging to 175 species across nine sites (eight 1-ha plots) located in dry, mesic and humid forests. We tested whether wood density varied across species, communities and habitats, and depended on mean annual precipitation (MAP), mean annual temperature (MAT) and an aridity index (AI). We also tested whether the variations observed in community mean wood density (WDmean) and in wood density standard deviation differed from those obtained by a randomized species distribution across communities. We constructed a phylogenetic supertree at genus level and tested for the non-random distribution of WDmean. Results We found that WDmean tended to increase with increasing aridity (i.e. decreasing MAP and increasing MAT) and was significantly higher than expected under randomized species distribution at the dry forest site only. However, some species with low wood density grew well at these dry sites. At genus level, wood density was not random within the phylogenetic supertree. Some lineages exhibiting higher wood density than expected by randomization were also the most represented at the dry sites. Conclusions Although we did not observe an environmental filter sensu stricto, aridity associated with a low MAP and a high MAT at the dry and mesic forest sites was likely to favour species with a high wood density. Our phylogenetic results suggested that species belonging to a few lineages exhibiting high wood density were likely to be adapted to drought, hence favoured by increasing drought. [ABSTRACT FROM AUTHOR]

the past, the circumscription of the large genus Psychotria (Rubiaceae) was difficult, until molecular phylogenetic studies revealed its considerable paraphyly, enabling the delimitation of its major lineages and the grouping of related genera, and most notably the separation of Psychotria and its relatives (former Psychotrieae) into two tribes: Psychotrieae and Palicou-reeae. The genus Margaritopsis, which is included in Palicoureeae, encompasses 27 Neotropical species, and in previous studies these have been shown to be close relatives of a group of eight Psychotria species that occur over a large region extending from South-East Asia to tropical South Pacific through Malesia (= the AMP region, defined as including South-East Asia, Malesia, tropical Australia, Melanesia, Micronesia, New Caledonia and Polynesia). A molecular phylogenetic study, using one nuclear DNA region (ITS) and four plastid DNA regions (ndhF, rpsló, tmH-psbA, trnT-F), is undertaken in order to test the place-ment of 17 AMP Psychotria species within Palicoureeae. The phylogenetic results show that they form a monophyletic clade (= clade G), which also includes the monotypic Fijian genus Readea and Hodgkinsoniafrutescens from Australia. Clade G is embedded in a well-supported grade with five Neotropical representatives of Margaritopsis. A morphological survey based on twenty characters, with the potential to circumscribe generic entities, shows that the monophyly of clade G is supported by a character combination that is similar to species of Neotropical Margaritopsis, confirming their inclusion in this genus. Taxo-nomic and nomenclatural work on these species is required to formalize nomenclatural implications. Based on the same set of morphological characters, but in absence of molecular data, 28 other Psychotria species from the AMP region were detected as likely candidates for inclusion in Margaritopsis, allowing the estimation of species richness of clade G to be a minimum of 47 species. Within clade G, five well-supported subciades and a Readea lineage are delimited and each of these is generally supported by unique morphological features. Phylogenetic topologies reveal biogeographical patterns, including a main route of dispersal from western to eastern parts of the AMP region, with subsequent dispersals between archipelagos in the region. [ABSTRACT FROM AUTHOR]

The article offers information on a proposal to conserve the name Margaritopsis against Eumachia of the family Rubiaceae. It informs that adoption of Eumachia for all species presently considered as Margaritopsis would create significant nomenclatural instability. It further informs that to preserve the stability of nomenclature within Rubiaceae, the conservation of the name Margaritopsis against Eumachia is proposed.