Lecanactis malmideoides is a little-known species of corticolous (bark-dwelling), crustose lichen in the family Roccellaceae.

Characteristics of the lichen include its pruinose discs, thin and glossy black margins, and ascospore structure.

[2] The thallus of Lecanactis malmideoides is continuous, minutely granular, dull, thin, and locally abraded.

The disc is brown, flat, and sparingly to thickly yellowish-green with pruina, with a glossy black margin about 0.05 mm wide.

[2] Lecanactis malmideoides is found on tree bark in a primary rainforest and at the time of its publication was known to occur only in Brazil.