Two new species and one new variety of Chascolytrum Desv. (Poaceae) are described and illustrated. Chascolytrum latifolium Essi, Souza-Chies & Longhi-Wagner and C. juergensii var. angustilemma Essi, Souza-Chies & Longhi-Wagner occur in the southern Brazilian highlands, while C. altimontanum Essi, Souza-Chies & Longhi-Wagner occurs in the Bolivian highlands. Chascolytrum latifolium is related to C. subaristatum (Lam.) Desv., but differs mainly by the wider leaf blades and by some characteristics of the palea. Chascolytrum altimontanum is related to C. paleapiliferum (Parodi) Matthei and C. subaristatum, the main differences being the presence of flattened trichomes at the lemma base and the shape of the spikelets. Specimens of all these new taxa were included in a parallel molecular analysis, with the results supporting the new taxa as genetically divergent from the closest morphologically related species. In addition, Briza juergensii Hack. is transferred to Chascolytrum for the new combination C. juergensii (Hack.) Essi, Souza-Chies & Longhi-Wagner.