Insights into The Diversity of Nepenthes L. (Nepenthaceae) Across Peninsular Malaysia, Including The First Sighting of an Undescribed Taxon with Flared Peristomes and Quadruple-Row Ventral Wings

The discoveries of six taxa between 2019 and 2022 have brought the total number of Nepenthesspecies occurring in Peninsular Malaysia to 18. This article serves as a comprehensive overview, incorporating the latest information and taxonomic insightsconcerningallspecies native to the peninsula. The information is derived from published taxonomic records and cumulative field observations conducted since 2013.Notably, it further reports heretoforeundocumented discoveries, making it a significant contribution to the current knowledgeof tropical pitcher plants. Theseinclude a sighting of a population of Nepenthes with unusual traits in the upper montane forest of Banjaran Titiwangsa, which may represent the 19thtaxonin Peninsular Malaysia. The plantsexhibit conspicuously expandedperistomes and an unusual wing morphology, which altogether provide compelling evidence supporting the recognition of these individuals as a distinct and previously unknown species. Therefore, a provisional taxonomic name—Nepenthessp. Titiwangsa (pesonawangsa_223) A. Amin—is assigned.The species is inferred to belongto the N. macfarlaneigroup based on its toothed peristome and the presence of fine hairs below the lid. The partial description, speciesnote, photographs,and a dichotomous keyof the proposednew speciesare provided.In addition, a velvety N. sanguineapopulation has been observed in northern Banjaran Titiwangsa and treated as a new natural variation (var. velutina) in this article.