The female type specimen was described as having a dull ochre-orange coloration on the head, pronotum, and underside of the abdomen, with sides of the pronotum (the plate behind the head) and its transparent tegmina a dull ochre, and the mesonotum (plate behind the pronotum), metanotum (plate behind the mesonotum), and back of its abdomen a russet color.

Other female specimens were more intensely colored, with the head, pronotum, mesonotum and metanotum a russet color, the pronotum shading to ochre-tawny on its sides, the abdomen a shining blackish-brown, and the tegmina mostly a transparent russet.

Hebard's 1917 description included measurement ranges based on 7 male specimens and 4 female specimens:[5] Among males of the species, the dorsal surface (back) of the abdomen is unspecialized, a characteristic shared with only one other species of the genus Parcoblatta, Parcoblatta bolliana.

Males of species are distinguished by P. desertae having a pale head, moderately decided sulci (grooves) on its pronotum, and a distance between its compound eyes much wider than that between its ocelli, while the P. bolliana has a dark head, very decided sulci on its pronotum, and a distance between its compound eyes no wider than that between its ocelli.

Distinguishing characteristics are that female P. desertae are generally pale-colored, have elongate subtriangular tegmina, and the edges of their supra-anal plates form a broad, weak triangular shape at the base of their cerci, while female P. uhleriana are rust-colored to very dark, have roundly subtriangular tegmina, and the edges of their supra-anal plates converge in a weakly concave fashion.