How do you describe a keynote species?

A keynote species is a species that has a disproportionately large impact on its ecosystem relative to its abundance. Its presence or absence significantly influences the structure and function of the community, often shaping the habitat for other species. Keynote species can be predators, prey, or plants that play crucial roles in nutrient cycling, habitat formation, or food webs. Their protection is often essential for maintaining biodiversity and ecosystem stability.