Pantomorus brunneus is characterized by the brown-whitish vestiture composed of round, smooth and not overlapped scales, and pale, long and erect elytral setae. Antennae are very short, with scape reaching half length of eye and funicular articles 1º and 2º subequal in length; humeri are rounded and corbels of the hind tibiae are well developed.
This species is similar to Pantomorus minutus from Bolivia and to some species Asymmathetes Wibmer & O’Brien 1986, from Ecuador.
Unknown.
Associated with native vegetation of the Yungas biogeographic province, above 1000 masl.