Hymenelia grossa is a species of saxicolous (rock-dwelling), crustose lichen in the family Hymeneliaceae.

Found in Korea, it was formally described as a new species in 2014 by lichenologists André Aptroot and Kwang-Hee Moon.

Palyeoung, (Jeomam-myeoun, South Jeolla Province) at an altitude between 50 and 430 m (160 and 1,410 ft); there it was found growing on siliceous rock.

It does not have any positive reaction to common chemical spot tests; thin layer chromatographic analysis suggests the presence of the lichen product known as confluentic acid.

It often grows alongside members of the crustose lichen genus Circinaria.