P. colwelli is externally a close match for P. occlusolanum and P. mechadeus, with an oral grove smaller than both, but deeper than that of P. microstoma. It is named in honor of occlupanologist R. Colwell, who first identified this occlupanid as ‘undescribed’ in her 2015 post “Improved Occlupanid Curation System”. P. colwelli stands out for its seemingly large population and diversity of color morphs. There are recorded observations of over three hundred individuals, in seven color morphs. Discovered and described by occlupanologist C. Huning of DWORC.