<em>Comatricha longipila</em> is a myxomycete in the order Stemonitidales, class Myxomycetes, belonging to the species-rich genus <em>Comatricha</em>. The species name reflects a taxonomic characteristic used in its identification, as capillitial and spore features are the primary diagnostic traits for distinguishing species within this genus. <em>C. longipila</em> inhabits decaying woody substrates and moist organic debris in forested and shaded environments. It passes through a conspicuous plasmodial stage in which a macroscopic, multinucleate mass of cytoplasm moves across and through substrates in search of bacterial and fungal food sources. The species subsequently forms fruiting bodies that release spores for aerial dispersal. Like all myxomycetes, this organism does not possess conventional physical traits such as body length or mass, and no quantitative biological data are recorded for this species. It has not been assessed by the IUCN.