New Guinea, the most botanically diverse island on the planet, is the location for one of the boldest conservation initiatives. The Manokwari Declaration aims to achieve 70% conservation designation for the Bird's Head Peninsula. This is 40% higher than the 2022 Global Biodiversity Framework target. However, there is a lack of species occurrence data to support evidence of where biodiversity can be best protected. To address t...

Summary Planchonella is the largest genus in subfamily Chrysophylloideae (Sapotaceae) and includes 97 described species distributed from the Seychelles to Hawaii with the greatest species diversity in Australia, New Caledonia and New Guinea. There are approximately an additional ten taxa that do not easily conform with known species limits, and/or have been identified by molecular methods as new to science. We describe here fo...

Two species of Tapeinosperma new to science are described from Papua New Guinea and the Solomon Islands: T. longipedicellatum Utteridge, Damas & Lepschi and T. purpureum Utteridge, Damas & Lepschi. Each species is illustrated, and a preliminary conservation status is given.

Summary Ventilagineae (Rhamnaceae) is a tribe of palaeotropical climbing plants, comprising two genera: Smythea and Ventilago . Previous studies have established the monophyly of the tribe, but the relationships within it remain unclear. This research includes six species of Smythea and seven species of Ventilago in a molecular phylogeny using the Angiosperms353 probe set. The results show that Ventilago is paraphyletic, with...

Summary The genus Maesa in New Guinea is revised. Thirty-nine species are accepted in this study and a key to species (including incompletely known taxa) is presented; four new species, M. begoniifolia, M. pilosopapuana, M. serratifolia, and M. tagulensis are described, and a neotype is selected for the widespread Indonesian species M. tetrandra . Distribution, habitat, phenology and detailed taxonomic notes are provided, and...

Summary Chionanthus is the largest genus of Oleaceae in New Guinea and, of its 17 species on the island, eight are new species described and illustrated here. Its high level of endemism, 70% (12 species), is typical of the New Guinea flora. Most of these new species are restricted to Papua New Guinea but this is likely to be an artefact of lower collecting intensity in Indonesian New Guinea. However, the 17 species do not refl...

Summary The genus Hypobathrum in Thailand is revised, based on the morphological characters found in herbarium specimens from Thailand and neighbouring countries including Bangladesh, Myanmar, Cambodia and Peninsular Malaysia. In this study, three species of Hypobathrum are recognised, among them, H. venulosum is a newly recorded species in this region. An identification key is provided for the species, along with descriptions...

Aim Flower traits are critical to the mutualistic networks that underpin ecosystem function. However, the broad‐scale drivers of flower traits are unclear. Using the megadiverse islands of Malesia, we test three hypotheses: (1) Flower size, openness and colourfulness (i.e. the trend from white to colourful flowers) will decrease with increasing temperature, but not with increasing precipitation seasonality. (2) Flower size, op...

Summary Lasjia griseifolia Utteridge & Brambach, a member of the Proteaceae, is described and illustrated as a new species from the Indonesian island of Sulawesi. The new species is similar to L. erecta , also from Sulawesi, and morphological differences between the taxa are discussed; a line illustration and detailed notes on the conservation status are provided.

Summary The Winteraceae comprise 100 – 130 species in five to nine genera. The genus Zygogynum is currently thought to have a Papuasian-Pacific distribution and is only known from the western Pacific islands (New Caledonia, Vanuatu and the Solomon Islands), Australia and New Guinea, including the far western Bird’s Head Peninsula, but is not yet recorded from islands to the west of the Sahul Plate and the biogeographic boundar...

Summary The genus Ziziphus (Rhamnaceae) is revised for Borneo. 13 species are recognised using morphological evidence, including three new endemic species: Ziziphus cuspidata , Z. domatiata and Z. puberula . Borneo is therefore the island with the greatest known diversity of Ziziphus species. The area surrounding Mount Kinabalu is particularly diverse, with nine species occurring in Ranau. Two new varieties of Z. borneensis ar...

Summary The genus Thalictrum L. in New Guinea is revised based on morphological evidence. Full descriptions of the genus and the four taxa recognised are given. Two species are recognised: Thalictrum papuanum , widespread across New Guinea, and a new species described here; T. umbraticola , endemic to west New Guinea. Two new varieties are described: Thalictrum papuanum var. acutisegmentum and T. papuanum var. laticarpellum. O...

Background and aims Ultramafic soils have high metal concentrations, offering a key opportunity to understand if such metals are strong predictors of leaf stoichiometry. This is particularly relevant for tropical forests where large knowledge gaps exist. Methods On the tropical island of Sulawesi, Indonesia, we sampled forests on sand, limestone, mafic and ultramafic soils that present a range of soil metal concentrations. We...

Summary The climbing genus Gouania (Rhamnaceae) is revised in western Malesia. Five species are recognised for the Philippines and Sundaland using morphological evidence, including a new species from the Philippines: Gouania longipedunculata . A taxonomic treatment, including a preliminary IUCN conservation status assessment, is presented for each species.

Summary Diplycosia papuana (Ericaceae: Vaccinioideae: Gaultherieae), a new endemic species from central New Guinea, is described and illustrated here. Notes on the distribution, ecology and conservation status of the new species, as well as a consideration of closely related species, are provided.

Summary The type specimen of Maesa camptobotrys is re-examined and morphology and characters are discussed. The specimen is a member of the genus Sabia (Sabiaceae) rather than the genus Discocalyx (Primulaceae) into which it was transferred; the name is formally placed as a synonym of Sabia pauciflora .