Recircumscription of the Nepenthes alata group (Caryophyllales: Nepenthaceae), in the Philippines, with four new species

An overview of Nepenthes in the Philippines is presented. Four new species, Nepenthes extincta sp. nov., N. kitanglad sp. nov., N. kurata sp. nov. and N. leyte sp. nov. are described and illustrated from the Philippines and placed in the Nepenthes alata group. An updated circumscription and key to the species of the group is provided. Delimitation and comparison with the Regiae group is given. All four of the newly described species are assessed as threatened using the International Union for the Conservation of Nature 2012 standard, and one, N. extincta sp. nov. is considered likely to be already extinct due to open-cast mining. Logging and conversion of forest habitat are thought to be the main threats to the other three species.