Chrysolykos calceatus is a freshwater chrysophyte microalga in the genus Chrysolykos, class Chrysophyceae, order Chromulinales. The genus Chrysolykos belongs to the loricate chrysophytes, a group of golden algae enclosed within a rigid or semi-rigid outer case through which flagella emerge. The specific epithet calceatus — meaning shoed or boot-shaped — describes the characteristic shape of the lorica in this species, which resembles a shoe or boot in lateral profile, a morphology distinctive enough to separate it from the angular profile of C. angulatus and the flattened form of C. complanatus. C. calceatus has been recorded from Norwegian freshwater environments, part of the documentation of chrysophyte diversity in cold Scandinavian lake systems. Scandinavian oligotrophic lakes are important habitats for loricate chrysophytes, which thrive in their clear, low-nutrient waters during stratified warm seasons when competition from larger algae is reduced. The species is a nanoplankton organism engaged in photosynthesis using the chrysophyte pigment complement, and may additionally practice phagotrophy on bacteria and small organic particles. Stomatocyst formation — the production of siliceous resting cysts — is a feature shared across many chrysophytes and may occur in C. calceatus, providing resistance to unfavorable seasonal conditions such as winter ice cover or summer thermal stratification. C. calceatus has not been formally assessed under IUCN criteria and is classified as Not Evaluated. Documentation of this species contributes to knowledge of freshwater microalgal biodiversity in boreal and subarctic ecosystems.