Phlegmariurus talamancanus is a narrow endemic found in paramos of central Costa Rica and a few localities in western Panama. It differs from Phlegmariurus crassus (with which is co-occurs throughout its range) by a lack of heteroblastic shoot differentiation, slightly larger and often less appressed leaves, and several leaf epidermis characters.

It is a common herb in paramo habitats in the Cordillera de Talamancana of south-central Costa Rica, where this specimen was collected. Note the slightly swollen leaf bases in the close-up image; this is caused by air cavities in the leaf bases. Other prominent Phlegmariurus species at this site are P. crassus and P. attenuatus; several others are rare in these habitats.