R. densiareolata Loefgren
Info from Backeberg’s Lexicon

Reduced to synonymy under R. lindbergiana by Barthlott and Taylor Bradleya 13

• Body shrubby, trunk more or less erect at first, then hanging, to 60 cm long.. 1-1.2 cm thick;
• Shoots 6 - 7 together, never whorled, 20-60 cm long., 5-7 mm thick, more or less tapering at the tip, light yellowish-green, later grey;
• Areoles crowded, spiralled, on younger shoots with bristles 1-1.5 mm long;
• Flowers very numerous, ca. 9 mm diam., white;
• Ovary without scales;
• Fruit pinkish-red, ovoid.
• Habitat Brazil (Rio de Janeiro, near Tijuca).