Four species of the genus Sticta are described as new from Bolivia, based on morphological examination and phylogenetic analysis of the fungal ITS barcoding marker. Additionally, two species are reported as new to Bolivia (their identification confirmed by molecular data) and one previously reported species is confirmed by molecular data for the first time. Detailed morphological and anatomical descriptions are provided for all new species. Two of the new species, S. isidiolobulata Ossowska, B. Moncada, Lücking & Kukwa and S. madidiensis Ossowska, B. Moncada, Lücking & Kukwa belong to clade I, as defined in previous studies. In contrast, S. montepunkuensis Ossowska, B. Moncada, Lücking & Kukwa and S. macrolobata Ossowska, B. Moncada, Lücking & Kukwa, also described here as new to science, belong to clade III. Sticta isidiolobulata has an irregular to suborbicular thallus of medium size, with isidia developing into spathulate lobules, cyanobacterial photobiont and apothecia with entire to weakly-crenate margins. The large irregular thallus of the cyanobacteria-associated S. macrolobata has broad lobes, apothecia with verrucous to tomentose margins and cyphellae with raised margins, whereas S. madidiensis has a medium-sized, palmate to irregular thallus with a stipe, but without vegetative propagules and apothecia. Sticta montepunkuensis has large and irregular thalli with green algae as photobiont, apothecia with crenate to verrucous margins and urceolate cyphellae with a wide pore and a scabrid basal membrane. Two species, S. beauvoisii Delise and S. riparia Merc.-Díaz are reported as new to Bolivia (the latter also as new to South America) and belong to clade III. Sticta tomentosa (Sw.) Ach., species confirmed from Bolivia by molecular data, belongs to clade II. Sticta beauvoisii is characterised by a smooth yellowish-brown upper surface with darker apices and abundant, marginal isidia and a brown lower surface with golden-chocolate brown primary tomentum and sparse, golden-brown rhizines. Sticta riparia has a strongly branched thallus, with undulate lobes and abundant, marginal, palmate, grey to dark brown phyllidia and greyish-brown lower surface with the primary tomentum absent towards the margins. Sticta tomentosa has palmate, bluish thalli with white cilia and abundant, submarginal apothecia and creamy-white lower surface with a sparse, white primary tomentum.
