Dwarf white isopods are a small isopod species (Trichorhina tomentosa) native to the Galapagos Islands and other tropical zones within the Americas. They're grayish-white and about 1/3rd the size of most other common isopods in the hobby.
They reproduce parthenogenetically, so all dwarf white isopods are females. Since every adult isopod is able to produce offspring - rather than requiring a pair of two adults - they're extremely prolific.
Dwarf whites are efficient at removing organic waste in a bioactive terrarium, but their small size also makes them a great food source for small insectivores, like dart frogs and dwarf geckos. Because they're so small, they're flighty, and they usually stay hidden well enough to maintain their population even when there's a small reptile or amphibian picking off the unlucky ones.
While they'll do best in a tropical habitat with temperatures in the 80s and humidity around 80%, dwarf white isopods are adaptable and capable of surviving and reproducing at room temperature with humidity around 50%.