Diselma archeri is endemic to Tasmania and is the only species in this genus. The adult leaves are scale like, overlapping like tiles and are opposite and decussate so form four rows up the stem. These leafy stems are only about 1-1.5 mm across and square in cross section. Seedlings are uncommon (this species often resprouts from trunks buried in the peat), but have narrow, spreading leaves a few mm long. The female cones are small (~3-4mm across) and dry, containing about 4 seeds.

This species is often confused with Microcachrys tetragona and Phaerosphaera hookeriana, both of which live in similar areas to D. archeri. P. hookeriana has similar growth habit to D. archeri, but has spirally arranged leaves. M. tetragona is generally prostrate (although D. archeri can also be of similar size), has no stomata on the outer surface of the leaf and has conspicuous red fleshy female cones.