Prototrichia metallica is a slime mould species from the order Trichiida and the only species from the genus Prototrichia. It is mainly distributed on mountains.

Prototrichia metallica is a very variable species. The plasmodium is white. The fruit bodies are grouped densely.^[1] They are orange brown to dull brown, occasionally pink, short stemmed or are lying on a heavily regenerated edge, rarely plasmodiokarp sporokarps with a diameter from 0.5 to 2.2 mm. The membranous peridium is transparently thin and shinily iridescent-coloured. Its surface is composed of a coarse mesh arrangement of wrinkled lines, along which it later divides into pieces.^[1][2]

The capillitium is often irregular, usually due to the presence of several yellow-brown, translucent spirally banded strands, which divide towards the outer end. The branches are often intertwined spirals, which sometimes form a network. Many of the outer ends are fused with the upper part of the peridium wall. The spirals are occasionally missing. The thorny spores are pink as mass,^[1] orange-brown to brown, individually yellow and have a diameter from 10 to 13, rarely up to 15 µm.^[2]

Prototrichia metallica has been found in mountainous area of Tasmania, Europe, western North America and South America. It was first found in South America in 1976. It is a "nivicol", meaning that it grows on the snow line at the time of snowmelt.^[1][3]

The species was first described in 1859 as Trichia metallica by Miles Joseph Berkeley and the genus in 1876 by Joszef Tomasz Rostafinski.^[2] Prototrichia was for a long time classified in Dianemidae, periodically even as a separate family of Prototrichiaceae. Since the end of the 1960s, it was asserted that this species is part of Trichiidae. Charles Meylan described in 1921 a further species, Prototrichia schroeteri, and the name is usually the synonym. Nowotny, however, believes that it is a separate species.^[1][4]