Chrysococcus rufescens is a loricate chrysophyte alga in the genus Chrysococcus. The specific epithet rufescens (Latin: reddish or becoming reddish) likely refers to a brownish-golden coloration of the lorica or the pigmented cell contents visible under light microscopy, reflecting the characteristic golden-brown color imparted by fucoxanthin and related carotenoids in chrysophyte chloroplasts. The lorica of C. rufescens encloses the cell and has an apical opening through which the flagellum extends. The species inhabits freshwater environments in northern Europe, including lakes and ponds in Scandinavia. Golden algae (chrysophytes) are typically most abundant in oligotrophic, cold, and poorly buffered waters, making them sensitive indicators of environmental change. C. rufescens contributes to primary production and the microbial food web as a mixotrophic nanoplankton organism capable of both photosynthesis and bacterivory. Chrysophyte loricas are preserved in lake sediments as stomatocysts and scale assemblages, providing long-term paleoecological records. The species has not been evaluated for conservation status by the IUCN and is categorized as Not Evaluated. Accurate identification of C. rufescens requires electron microscopy of lorica ultrastructure.