The species epithet polycarpa is derived from the Greek words for 'many' and 'fruit', referring to the abundance of apothecia, which are a type of fruiting body found on the lichen.

The holotype was collected in the Baihuashan National Nature Reserve in Beijing's Mentougou District, at an elevation of 1,120 m (3,670 ft).

[1] Reproductive features include numerous apothecia that cover the upper surface, starting as small dots and enlarging to up to 0.48 mm with a pale yellow or body-coloured rim.

The internal tissue of the apothecia (hymenium) is wine red when treated with iodine, and the spore-producing sacs (asci) are club-shaped, containing over 100 spores each.

[1] Peltula polycarpa grows on granite surfaces that are periodically moistened by water, such as those found alongside mountain roads.