The genus AporiusKuschel, 1955, described based on the single species Hadropus brevipennisChevrolat, 1879 from French Guiana, is herein transferred from the tribe Tanymecini, subtribe Piazomiina to the tribe Naupactini, new tribal placement, because it shares the typical characters of this tribe, except the presence of connate tarsal claws. Within Naupactini, Aporius is probably related to Hadropus Schoenherr, 1826, based on the morphology of the rostrum, antennae, and genitalia. We redescribe and illustrate the genus Aporius and its single species, and we provide a key to separate it from Hadropus. We also discuss the taxonomic status of the remaining members of South American Piazomiina and assign the genus Galenactus Kuschel to Leptopiini, new tribal placement, thus removing Piazomiina from occurrence in South America.