A new Wedding Bush from the eastern goldfields of Western Australia (Ricinocarpos digynus: Euphorbiaceae)

Abstract

Ricinocarpos digynus Hislop & Wege is the first addition to Ricinocarpos Desf. (Euphorbiaceae: Ricinocarpeae: Ricinocarpinae) since Halford and Henderson’s (2007) taxonomic revision in which 28 species were recognised, all of them endemic to Australia. As part of this study, Halford determined a single specimen of R. digynus (J. Bale 313), collected from the Kambalda area in 1966, as R. stylosus Diels s. lat. with a notation that the specimen was atypical in its ‘longer leaves and spreading rather than appressed petioles’. That it was not confirmed to represent a new taxon at this time is unsurprising since the material not only lacks fruit but the female flowers are in early bud. The recent discovery of a second population on a mining lease north of Kalgoorlie by Andrea Williams of Botanica Consulting, and her repeated site visits to obtain fruiting material, has assisted its taxonomic resolution. We describe this new and distinctive species below, bringing the number of Western Australian Ricinocarpos species to 19 (Western Australian Herbarium 1998–) of which seven are conservation-listed (Smith & Jones 2018).