Being of a scientific mind (but also kinda lazy) I went searching the literature for snails in Peru and quickly found a 1996 paper by Vivar and colleagues. Although it was covering only a small region, it looked promising because it listed species found by previous studies. Here are the snails listed, with updated names in some cases.
Species listed: Updated/clarified name/or possibility.
Physa venustula: Physa acuta.
Aplexa peruviana: Maybe Aplexa mangerae, known from Mexico.
Lymnaea cubensis: Same except put into cubensis/viator complex.
Ancylus concentricus: Uncancylus concentricus
Helisoma trivolvis: Same.
Helisoma peruvianum: Same, I think, but suspect.
Helisoma duryi: Planorbella duryi
Drepanotrema kermatoides : Same
Melanoides tuberculata : Melanoides tuberculata
Littoridina cumingii: Heleobia cumingii
Ten species is not a very impressive list, but this is from one small region. Surely there are more species. This is when I ran into the USA bias. There have been studies done, and are still being done, where results were not published in English. I know what you’re thinking, OMG, really?
Turns out there is a paper in Spanish (Rameriz et al 2003) that tried to gather all the reports on mollusks of Peru: They list 129 freshwater mollusk species, and 89 are freshwater snails. An impressive display of diversity, however, this still seems low for a large country crisscrossed by rivers with coastal regions, tropical forests, and hillsides leading into the Andean mountains, as well as a huge lake at a very high elevation (Lake Titicaca). A vast array of habitats and microhabitats. The indeed authors suggest that more diversity exists since relatively little work has been done on snails in Peru.
One of the interesting aspects of this review paper on Peruvian mollusks is the number of endemic species (species not found elsewhere). They list 64 species of endemic freshwater snails. Eighty-nine species, sixty-four of which are endemic to Peru. That is an amazing result. However, let us be cautious. These species are likely to inhabit other South American countries, if not elsewhere, that have even fewer studies evaluating them. Also, take another look at the short list of ten species above. Some snails are listed as one species which is likely a different species. take for example Physa venustula this snail is actually Physa acuta, the most cosmopolitan snail on the planet. This is a common problem in freshwater gastropod taxonomy, naming more species than actually exist, they acknowledge this in the paper, particularly in regard to Pomacea: Twenty three species of this genus in Peru, however, the systematics are undergoing changes and confusion rains currently (and current when this paper was written). Pomacea is a genus of Apple Snails, family Ampullariidae. South America is the central zone for Apple snails so 23 species, out of 39 currently recognized, may be correct, but…
I visited Peru recently and discovered a few things, one of them in line with the journal article in Spanish that I attempted to wade through, that is, I don’t know nearly enough Spanish. The other is that it is hard to find snails while you’re pausing for a rest break as your guide explains the details of Incan life.
I searched for some snails in the Urubamba River, the one that flows at the base of Machu Picchu, and observed a single species, Physa acuta. I searched the forest undergrowth for terrestrial snails, without any luck. On the streets of Cusco at a stand selling snail mucous (a new fade in skincare), they had displays of two terrestrial snails, Megalobulimus maximus, a large snail found in the forest, and a garden snail (listed as genus Helix in the Ramirez review paper but now placed in the genus Cornu) Cornu aspersum. In the picture attached the seller is pointing to Cornu aspersum, the big mothers around it are Megalobulimus maximus of course. What a massive and awesome-looking snail.
Feliz día de acción de gracias, cuídate.
Sources and Further Readings:
Ramírez R, Paredes C, Arenas J. 2003. Moluscos del Perú. Revista de Biología Tropical 51(3): 225-284.
Vivar R, Larrea H, Huaman P, Yong M, and Perera G. Some ecological asp[ects of the freshwater molluscan fauna of Pantanos de Villa, Lima, Peru. Malacological Review 29: 65–68.