Statistical analyses of two morphological datasets, including 190 newly measured specimens, showed that individuals of Myosotis (Boraginaceae) from Te Waipounamu / South Island, Aotearoa, New Zealand, identified a priori with three different informal tag names, belong to the bracteate–prostrate group, are morphologically distinct from each other and from other species, and merit scientific description. Myosotis hikuwai Meudt, Prebble & G.M.Rogers is known from one location near Wānaka (Otago), has an unusual erect, spring annual habit, and is most similar to M. brevis and M. glauca, with which it is sympatric. Myosotis venticola Meudt & Prebble comprises plants that were sometimes previously identified as M. cheesemanii from certain ranges in Otago and southern Canterbury, but with retrorse trichomes present on the abaxial and adaxial side of the rosette leaves. Myosotis ultramafica Meudt, Prebble & Rance comprises individuals from ultramafic sites in certain ranges in Southland, and is most similar to M. cheesemanii and M. lyallii. We recommend that all three new species are listed as Threatened under the New Zealand Threat Classification System. In addition to descriptions and illustrations, the three new species are also included in a revised key to the nineteen species of southern hemisphere bracteate–prostrate Myosotis.