Two new species of Currant Bush Coprosma (Rubiaceae) from an endemic radiation on Lord Howe Island

Molecular and morphological evidence provide support for the description of two new species of Coprosma (Rubiaceae) from Lord Howe Island, a remote oceanic island in the Tasman Sea. The first species, C. savolainenii sp. nov., was discovered during a plant survey, whereas the second species, C. ptotopetra sp. nov., was identified using DNA fingerprinting. Confirmation of both is currently being obtained through high-throughput sequencing. We provide detailed descriptions of each new species, alongside an updated description of C. putida, a species with similar morphology to C. ptotopetra sp. nov.. We also provide phenological, distribution, and conservation data for each species. This description goes beyond a traditional species account, as it represents a unique endemic radiation occurring in sympatry on an isolated island of global conservation significance. It may also represent a rare botanical example of the syngameon hypothesis, where hybrid speciation accelerates evolutionary radiation.