Culex rajah is a species of mosquito in the genus Culex. It is endemic to Sabah, Malaysian Borneo. C. rajah is placed in the subgenus Culiciomyia. In its larval stage, C. rajah is found exclusively in the pitchers of Nepenthes rajah (hence the name), a species of pitcher plant. As such, it is considered a nepenthebiont.
Species taxanomy provided by GBIF Secretariat (2022). GBIF Backbone Taxonomy. Checklist dataset https://doi.org/10.15468/39omei accessed via GBIF.org on 2023-06-13; License: CC BY 4.0