P. longus bears a close external similarity to Porrectofrontus rubikarloffia, but sports a narrower oral groove. The oral groove of P. longus is similar to that of Palpatophora utiliformis, while P. rubikarloffia appears to have an oral groove like that of Porrectofrontus occlusolanum. Only three P. longus have been observed, two yellow, and one green. Discovered and described by occlupanologist C. Huning of DWORC.