Abstract
Miconia angustidentata, from upland rain forest in northwestern Guyana, is described, illustrated, mapped, and compared with its superficially similar species based on morphological features. It is characterized by its ovate to elliptic 3–5-nerved entire leaves; axillary clusters of 3–5 sessile mostly 5-merous flowers; sparse cover of minute stellate trichomes on abaxial foliar surfaces, hypanthia, and calyx lobes; conspicuous oblong calyx teeth that obscure calyx lobes at anthesis and in fruit; white oblong petals that lack a subapical mucro on the abaxial surface; white stamens with ventrally inclined anther pores; (4–) 5-locular superior ovary; and ovoid-pyramidal angulate seeds with an irregularly rugulate testa and a raphe that extends about 50% the length of the seed. A conservation assessment of Endangered is recommended for this species based on IUCN Red List Categories and Criteria.