Abstract
Five genera of the largely southern hemisphere family Cunoniaceae occur in the Solomon archipelago (Solomon Islands plus the Autonomous Region of Bougainville, Papua New Guinea): Geissois, Pterophylla (previously Weinmannia p.p.), Spiraeanthemum, Schizomeria and Ackama (including Spiraeopsis) (total of 12 species); the first three genera are also found in Vanuatu (total of four species). None of the genera is endemic to these two archipelagos although more than half the species are and Spiraeanthemum macgillivrayi Seem. is the only species common to both island groups. Along with keys to the genera and species, accounts are given for G. denhamii Seem. (throughout Vanuatu), G. pentaphylla C.T.White (restricted to the island of Vanikoro, Solomon Islands), and P. makiniae H.C.Hopkins, J.Bradford & Pillon sp. nov., from Vangunu and Kolombangara in the Solomon Islands. Most of the remaining taxa have been revised for generic treatments or flora accounts and for these, only a synopsis is given with notes on types for some names. Provisional conservation assessments are provided, with ecological summaries. Generic diversity in the Cunoniaceae decreases eastwards across the Pacific Ocean to the Marquesas and Austral Islands. The islands in the western Pacific have surprisingly few genera in common with Australia, and, compared with New Caledonia, Fiji or the Solomon archipelago, Vanuatu has fewer taxa than might be predicted from its location and size, presumably because of its young geological age.