Rhizocarpon diploschistinum[1] is an uncommon species of lichenicolous (lichen-dwelling), crustose lichen in the family Rhizocarpaceae.

[3] The thallus of Rhizocarpon diploschistinum is areolate and varies in colour from very pale yellowish-tan to an intense fluorescent yellow.

The secondary chemistry of Rhizocarpon diploschistinum includes rhizocarpic acid, and its cortex has a UV+ (orange) reaction.

[3] Rhizocarpon diploschistinum has been found exclusively in shrub steppe and grasslands in central Washington and north-central Oregon in the United States.

It grows on Diploschistes muscorum, which is typically found on soil and grass stubble in areas with well-developed biotic crusts and minimal grazing.