Platythecium hypoleptum is a species of corticolous (bark-dwelling), crustose lichen in the family Graphidaceae.

The lichen was first formally described as a species new to science in 1863 by Finnish botanist William Nylander, as a member of the genus Graphis.

The type specimen was collected in Nova Granada (Brazil), at an altitude of 2,400 m (7,900 ft).

[2] In 2002, Bettina Staiger proposed a transfer to genus Thalloloma, based on a reorganisation of family Graphidaceae that stressed the importance of ascocarps and their accessory organs as characteristics to delimit genera.

[3] A year later, Minoru Nakanishi and Hiroyuki Kashiwadani suggested that the taxon should instead be in genus Platythecium.