Polymeridium submuriforme is a species of corticolous (bark-dwelling) lichen in the family Trypetheliaceae. It occurs in the Philippines. This lichen is characterized by its pinkish-grey thallus, which does not fluoresce under ultraviolet light. P. submuriforme is similar to Polymeridium cinereonigricans but can be distinguished by its much smaller and . The ascomata measure 0.3âÂÂ0.6 mm in diameter, with a solitary, spherical that is . As the ascomata age, the wall expands up to 0.2 mm sideways. The ostiole is apical, and the hamathecium is inspersed. The number 6âÂÂ8 per ascus, iodine-negative, somewhat , and measure 18âÂÂ20 by 6âÂÂ7.5 üm. These ascospores are not ornamented and are surrounded by a 1âÂÂ2 üm wide gelatinous sheath. No chemical substances have been detected in this lichen. The type specimen was collected from Leyte on tree bark.