Two unknown Euphorbiaceae were discovered during the environmental impact study for a proposed nickel mine behind Weda Bay on Halmahera in the North Moluccas (Maluku Utara Province) of Indonesia. Morphological comparisons and molecular phylogenetic analyses using four markers (plastid trnL-F and rbcL, and nuclear ribosomal ITS and ETS) indicated they should be recognized as constituting a new, distinct genus of two species, which are described and illustrated here as Weda fragarioides and W. lutea. The new taxa are members of the Australasian tribe Ricinocarpeae in subfamily Crotonoideae, and most closely related to Alphandia. In contrast with the otherwise mostly sclerophyllous Ricinocarpeae, Weda possesses stellate to dendritic hairs, large, long-petiolate, glandular leaves, and inflorescences with a pair of large, leafy, subopposite bracts. The two narrowly distributed species are distinguished from each other by vegetative and floral features, molecular data, and elevational preferences. Leaf elemental analysis of Weda indicated manganese but not nickel accumulation. Newly resolved generic relationships and potential morphological synapomorphies within Crotonoideae are discussed, and the circumscription of Ricinocarpeae is expanded from 7 to 11 genera.

Data matrix is based on fluorescent Sanger sequencing of 4 genetic markers (trnL-F, rbcL, ITS, ETS) and 102 tips, which depending on marker were aligned with MAFFT ver.7.452 or inserted into a modified existing alignment (i.e., Wurdak et al., 2005).

Deletion sets (masking) and partitions are specified in the interleaved matrix, along with additional notes. The full data matrix can be executed with PAUP* to automatically exclude a 567 bp deletion set which was used for the main analyses.