Key it out from Fernando Rivadavia, Paulo Minatel Gonella, Paulo Takeo Sano & Andreas Fleischmann's paper: Elucidating the controversial Drosera montana complex (Droseraceae): a taxonomic revision.
I won't reproduce the entire key but assuming that other species have been eliminated:
9. Leaf obovate-cuneate to cuneate with geniculate vernation; apical tentacles conspicuously distinct, in number of 7–12, 4–9 mm long, with head with unifacial gland tip ....... D. tentaculata
- Leaf obovate, oblanceolate, or oblong-spatulate with circinate vernation; apical tentacles inconspicuously distinct, only up to 5 mm long ........ 10
10. Adaxial petiole surface densely eglandular-pilose; sepals ovate to sub-orbicular with rounded (subobtuse) apex, in bud forming a pyramidal projection at the fusion point between adjacent sepals ....... D. spirocalyx
- Adaxial petiole surface glabrous or sparsely eglandular-pilose; sepals oblong-ovate to narrowly-ovate with acute apex, not forming pyramidal projections as described above ....... 11
11. Leaves oblong to oblong-spatulate; petiole 0.2–0.5(–1) mm wide; glandular trichomes of similar length present throughout scape; generally flowering from December to March (rainy season) [also in Bolivia] ....... D. montana
- Leaves obovate to oblong-obovate; petiole 0.4–3.0 mm wide; glandular trichomes absent on the basal third of scape, but dense and larger towards the apex; generally flowering from June to September (dry season) ....... .D. tomentosa (12)
12. Scapes densely eglandular-pilose (villous) on the basal half, decreasing in density towards apex ....... D. tomentosa var. tomentosa
- Scapes exclusively glandular-pilose from base to apex, without notable eglandular indumentum, occasionally also sparsely
eglandular-pilose mostly towards the basal third ....... D. tomentosa var. glabrata