A new species of Leptotyphlops dulcis group is described from the central Brazilian Cerrado, which is diagnosed by rostral shape, general colour pattern, and number of middorsal and subcaudal scales. This taxon has been commonly misidentified as L. koppesi in some Brazilian collections and by some authors. Leptotyphlops koppesi was described from the municipality of Terenos, State of Mato Grosso do Sul, Brazil, based on a single specimen. Since its original description, only three subsequent records appear in the literature reporting additional specimens of L. koppesi. We redescrib the holotype of Leptotyphlops koppesi, defining its geographic range and diagnose this from all species of L. dulcis group. Data on morphometric and meristic variation are reported for the new species and L. koppesi as well. Comparisons are made between the new species and all other South American species of the L. dulcis group. The hemipenis of the new species has a narrow basal portion and a series of lateral flounces. This general hemipenial morphology is unique among Neotropical leptotyphlopids, otherwise known only from Atlantic Rainforest species L. salgueiroi.