New Guinea has the world's richest island flora.

New Guinea is the world's largest tropical island and has fascinated naturalists for centuries1,2. Home to some of the best-preserved ecosystems on the planet3 and to intact ecological gradients-from mangroves to tropical alpine grasslands-that are unmatched in the Asia-Pacific region4,5, it is a globally recognized centre of biological and cultural diversity6,7. So far, however, there has been no attempt to critically catalogue the entire vascular plant diversity of New Guinea. Here we present the first, to our knowledge, expert-verified checklist of the vascular plants of mainland New Guinea and surrounding islands. Our publicly available checklist includes 13,634 species (68% endemic), 1,742 genera and 264 families-suggesting that New Guinea is the most floristically diverse island in the world. Expert knowledge is essential for building checklists in the digital era: reliance on online taxonomic resources alone would have inflated species counts by 22%. Species discovery shows no sign of levelling off, and we discuss steps to accelerate botanical research in the 'Last Unknown'8.

Phylogenetic relationships and biogeography of Asia Callicarpa (Lamiaceae), with consideration of a long-distance dispersal across the Pacific Ocean -insights into divergence modes of pantropical flora.

There are about 140 species of Callicarpa L. 1753 (Lamiaceae), with more species richness in tropical to subtropical Asia and the New World. The genus might provide an insight into the amphi-Pacific disjunction pattern of tropical and subtropical vegetation. This study has greatly improved the phylogenetic underpinning for Callicarpa, derived from more inclusive taxonomic samplings, and employing data on both two-nuclear and eight-chloroplast regions. To address time and patterns of diversification in Callicarpa, we conducted divergence time and biogeographic analyses, and inferred shifts in the distribution areas across the phylogenetic clades. Our phylogenetic results show that Callicarpa is monophyletic with respect to the groups considered, and eight well-supported primary clades were discerned in the combined analyses. Our estimates indicated that the crown group of Callicarpa originates around the Late-Eocene (ca. 36.23 Ma) and diversification within most clades is concentrated in the Miocene and continued to the Pleistocene. In addition, our biogeographic analyses suggested that the probable ancestor of the Callicarpa crown clade originated in East Asia and Southeast Asia. Multiple dispersal and vicariance events contributed to the current distribution of the taxa. Furthermore, this genus expanded eastward out of East and Southeast Asia to the New World by long-distance dispersal, which inspired us to better understand the amphi-Pacific disjunct distribution.

Environmental stress influences Malesian Lamiaceae distributions.

Dual effects of spatial distance and environment shape archipelagic floras. In Malesia, there are multiple environmental stressors associated with increasing uplands, drought, and metal-rich ultramafic soils. Here, we examine the contrasting impacts of multifactorial environmental stress and spatial distance upon Lamiaceae species distributions. We used a phylogenetic generalized mixed effects model of species occurrence across Malesia's taxonomic database working group areas from Peninsular Malaysia to New Guinea. Predictor variables were environmental stress, spatial distance between areas and two trait principal component axes responsible for increasing fruit and leaf size and a negative correlation between flower size and plant height. We found that Lamiaceae species with smaller fruits and leaves are more likely to tolerate environmental stress and become widely distributed across megadiverse Malesian islands. How global species distribution and diversification are shaped by multifactorial environmental stress requires further examination.

Premna grandipaniculata (Lamiaceae, Premnoideae), a remarkable new species from north Myanmar.

A remarkable new Premna species from Myanmar, P. grandipaniculata Y.H.Tan & Bo Li (Lamiaceae), is here described and illustrated. It differs from all known congeneric taxa by having huge complicated panicles which have tertiary branches formed by spike-like thyrses. In Premna, such a spike-like thyrse is found in P. bracteata and P. interrupta, but those species can be easily distinguished from P. grandipaniculata by their habit, indumentum, leaf size and inflorescence structure.

Premna vietnamensis (Lamiaceae, Premnoideae), a distinct new species from the Central Highlands of Vietnam.

Premna vietnamensis, a distinct new species which is endemic to Gia Lai Province in Central Highlands of Vietnam, is described and illustrated. It is characterized by its calyx tube bearing a semi-globose fleshy appendage, which has not been reported before from all known congeneric taxa, as well as from the Lamiaceae. A phylogenetic analysis of the whole Lamiaceae based on a sampling including representatives from all 12 currently recognized subfamilies confirmed the placement of this new species within Premna of the Premnoideae. Morphologically and geographically, P. vietnamensis is most similar to P. stenobotrys, but differs significantly in many aspects.

A large-scale chloroplast phylogeny of the Lamiaceae sheds new light on its subfamilial classification.

Lamiaceae, the sixth largest angiosperm family, contains more than 7000 species distributed all over the world. However, although considerable progress has been made in the last two decades, its phylogenetic backbone has never been well resolved. In the present study, a large-scale phylogenetic reconstruction of Lamiaceae using chloroplast sequences was carried out with the most comprehensive sampling of the family to date (288 species in 191 genera, representing approximately 78% of the genera of Lamiaceae). Twelve strongly supported primary clades were inferred, which form the phylogenetic backbone of Lamiaceae. Six of the primary clades correspond to the current recognized subfamilies Ajugoideae, Lamioideae, Nepetoideae, Prostantheroideae, Scutellarioideae, and Symphorematoideae, and one corresponds to a portion of Viticoideae. The other five clades comprise: 1) Acrymia and Cymaria; 2) Hymenopyramis, Petraeovitex, Peronema, and Garrettia; 3) Premna, Gmelina, and Cornutia; 4) Callicarpa; and 5) Tectona. Based on these results, three new subfamilies-Cymarioideae, Peronematoideae, and Premnoideae-are described, and the compositions of other subfamilies are updated based on new findings from the last decade. Furthermore, our analyses revealed five strongly supported, more inclusive clades that contain subfamilies, and we give them phylogenetically defined, unranked names: Cymalamiina, Scutelamiina, Perolamiina, Viticisymphorina, and Calliprostantherina.