The new Ischnocolinae genus Catumiri is described. The species Cenobiopelma argentinense (Mello-Leitão, 1934), considered a junior synonym of Oligoxystre Vellard, 1924, is transferred to the present genus. Three new species are also described: C. chicaoi n. sp., from south of Bahia, Una; C. petropolium n. sp., from Petrópolis, Rio de Janeiro (type species); and C. uruguayense n. sp., from Lavalleja, Uruguay. Diagnosis, zoogeographical distribution and an identification key are provided for all species.