A single Afrocyclops pauliani was discovered in 1951 in a small freshwater pond near Antananarivo, Madagascar, and it has not been seen since.
Namibcypris costata was a freshwater ostracod crustacean, a kind of seed shrimp, possibly endemic to the southern Kaokoveld in northern Namibia.
A water beetle just under two inches long from Santo Antonio da Barra, Brazil. It could be extinct, or it could have been found in the bottom of a canoe in the Amazon.
The Socorro isopod or Socorro sowbug is a crustacean extinct in the wild, having been found in only one place, the thermal waters of Sedillo Spring in New Mexico where they thrived in water between 79 degrees and 91 degrees Fahrenheit until the city of Socorro diverted the spring for drinking water in 1947 after which the Socorro sowbug survived in an old water pipe that led to a horse trough and two concrete bathing pools, becoming extinct in the wild in 1988 when a tree root cut off water in the pipe.