Morphological Characterization and Conservation Assessment
Fresh samples of the putative new species, along with co-occurringR. banaoana , R. consueloae , and R. cf.aurantia , were collected and preserved in a 70% ethyl alcohol solution. As with most taxonomic studies on Rafflesia, limited material was available due to the rarity of the plant and poor accessibility; however specimens were observed at several stages of development (from bud to anthesis), both male and female. Specimens were deposited in CAHUP, LBC, and PNH (abbreviations according to Thiers 2019). Dissected flowers were examined and the floral parts measured using the ruler tool in Adobe Photoshop CC, calibrated using image pixels. Material was compared with that of closely related species (Table 1) . We follow the morphological species concept (Davis and Heywood 1963; Knapp and Vorontsova 2016), which emphasizes the importance of observable physical traits in identifying and categorizing species.
The provisional conservation status of the species was assessed following the criteria and categories of the IUCN (IUCN Standards and Peititions Committee 2022). The extent of occurrence (EOO) and area of occupancy (AOO) of the species were estimated with the Geospatial Conservation Assessment Tool (Bachman et al. 2011).