A taxonomic revision of the small mangrove genus Camptostemon (Malvaceae)

The true mangrove genus Camptostemon (Malvaceae) is becoming increasingly rare. This genus can be found in the Philippines, Borneo, Sulawesi, Maluku, Papua New Guinea, and Australia. Confusion remains over the taxonomic status of Camptostemon aruensis, endemic to Aru Islands, Indonesia. Therefore, a taxonomic revision is presented. Morphological characteristics, distribution maps, an identification key, and photographs of the species are provided. Based on type and type-locality specimens from the Aru Islands, C. aruensis is found to morphologically match C. schultzii. Camptostemon aruensis is a synonym of C. schultzii. Therefore, Camptostemon consists of two species, C. philippinensis (from the Philippines, Borneo, and Sulawesi), and C. schultzii (from Maluku, Indonesian Papua, Papua New Guinea, and northern Australia). Camptostemon philippinensis and C. schultzii are found in different geographic areas and do not share the same island.