https://www.gbif.org/species/8838450
https://bugguide.net/node/view/248280
https://en.wikipedia.org/wiki/Listroderes_costirostris
https://insecta.pro/ru/taxonomy/854513

https://www.inaturalist.org/taxon_changes/110258

Listroderes is one of the most annoying genera in the world. And it's been made more annoying by frustratingly incomplete work done on them in the past.

In his definitive, widely known and (relatively) easily accessible work on the genus, Morrone (1993) synonymised Listroderes obliquus Klug, 1829 and Listroderes difficilis Germain, 1895 with Listroderes costirostris Schoenherr, 1826. This is the origin of the synonymy that is most well known and used in the websites that @newrookie has referred to.

Later, Morrone (2002) published a short, often-overlooked note in an poorly-known journal in which he comes to a different understanding of the complex, based on the dissection of five male specimens. In this work, he considers each of these three taxa to be valid species.

The big problem is that while Morrone (2002) says that "males are recognized easily by their distinctive aedeagi", unfortunately "females of these species are impossible to separate". The bigger problem is that pathenogenesis is common in Listroderes, especially in those parts of the world where it has been introduced. Although Morrone (2002) provides a summary of the geographic distribution for each of these three species (theoretically L. obliquus is the only one of these three supposed to be in South Africa, but...), it is not clear to me what Morrone is basing this information on (given that the only five specimens he dissected were all from Argentina). As males are absent in almost all introduced populations, it seems to me that there is no way to work out what species (either singular or plural) might have been introduced where.

To summarise: this swap might be a mistake, but a small one and an understandable one in the context of the much larger mistake that is the L. costirostris complex. I'm content to leave it be for the time being, until further work has been done on the group. I have some ideas as to how this might be resolved, but no means and no plans to do so for the present. In the meantime, if you ever find any, collect them and keep them in ethanol until such a day as a hero/ine arises to deliver us all from this confusion.

Morrone JJ 1993. Systematic revision of the costirostris species group of the weevil genus Listroderes Schoenherr (Coleoptera: Curculionidae). Transactions of the American Entomological Society 119(4): 271--315. http://www.jstor.org/stable/25078579

Morrone JJ 2002. On the species of the Listroderes costirostris complex (Coleoptera: Curculionidae: Cyclominae). Neotropica 48:70--72 [Not available online]