Tags: Crustacean.
Gammarus acherondytes is a species of crustacean in family Gammaridae. It is endemic to the Illinois Sinkhole Plain of Monroe and St. Clair counties in southwestern Illinois including Illinois Caverns State Natural Area. Historically it was known from six caves but in a survey in 1995 the species was found at only three of the sites with one further site inaccessible. This species occurs only in underground streams. It was first collected in 1938 and described as a new species in 1940.