The Lake Pedder earthworm (''Hypolimnus pedderensis'') is an extinct

earthworm An earthworm is a soil-dwelling terrestrial invertebrate that belongs to the phylum Annelida. The term is the common name for the largest members of the class (or subclass, depending on the author) Oligochaeta. In classical systems, they we ...

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

in the

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Megascolecidae Megascolecidae is a family of earthworms native to Madagascar, Australia, New Zealand, Asia, and North America. At up to 2 meters in length, their large size distinguishes the Megascolecidae from other earthworm families. They are an essential par ...

. Its

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

''Hypolimnus'' is

monotypic In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unisp ...

. It was

endemic Endemism is the state of a species being found only in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also foun ...

to the

Lake Pedder Lake Pedder, once a glacial outwash lake, is a man-made impoundment and diversion lake located in South West Tasmania, Australia. In addition to its natural catchment from the Frankland Range, the lake is formed by the 1972 damming of the ...

area in

Tasmania Tasmania (; palawa kani: ''Lutruwita'') is an island States and territories of Australia, state of Australia. It is located to the south of the Mainland Australia, Australian mainland, and is separated from it by the Bass Strait. The sta ...

Australia Australia, officially the Commonwealth of Australia, is a country comprising mainland Australia, the mainland of the Australia (continent), Australian continent, the island of Tasmania and list of islands of Australia, numerous smaller isl ...

, prior to its flooding in 1972 for a hydro-electric power scheme. It is only known from the

holotype A holotype (Latin: ''holotypus'') is a single physical example (or illustration) of an organism used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of s ...

specimen collected from a Lake Pedder beach in 1971. A 1996 survey failed to find it and it is presumed extinct. The Lake Pedder earthworm mainly fed on microbes or algae on sand particles. Their feeding habits were seen to have a considerable impact on the banks of the lake, as the particles they consumed were deposited on the surface of the ground in the form of castings. As these castings were exposed to air, the soil was aerated, improving both the drainage and water holding capacity of the soil.

References

Megascolecidae Extinct animals of Australia Endemic fauna of Tasmania Invertebrates of Tasmania Lake Pedder Animals described in 1974 Taxonomy articles created by Polbot {{Annelid-stub