The Haplotaxida are one of two

orders Order, ORDER or Orders may refer to: * Categorization, the process in which ideas and objects are recognized, differentiated, and understood * Heterarchy, a system of organization wherein the elements have the potential to be ranked a number of d ...

within the

annelid The annelids (Annelida , from Latin ', "little ring"), also known as the segmented worms, are a large phylum, with over 22,000 extant species including ragworms, earthworms, and leeches. The species exist in and have adapted to various ecol ...

subclass Oligochaeta, the other being the

Lumbriculida The Lumbriculidae are a family of microdrile oligochaetes common in freshwater environments, including streams, lakes, marshes, wells and groundwater. They should not be confused with the earthworm family Lumbricidae. Many species and genera are ...

. No real common name exists, but they are simply referred to as haplotaxids. Given that the other clitellatan annelids are embedded between and around the Haplotaxida and Lumbriculida, the traditional ''Oligochaeta'' are a

paraphyletic In taxonomy (general), taxonomy, a group is paraphyletic if it consists of the group's most recent common ancestor, last common ancestor and most of its descendants, excluding a few Monophyly, monophyletic subgroups. The group is said to be pa ...

assemblage. Thus, the Haplotaxida might eventually be up-ranked to subclass status within the ''Clitellata'' or an expanded Oligochaeta, with the present suborders advancing to order rank. The latter – though without merging the ''Oligochaeta'' and ''Clitellata'' – has been proposed time and again in the past, most prominently for the distinct ''

Moniligastrina Moniligastridae is a family of earthworms native to South and Eastern Asia, containing around 200 species and five genera. Genera *'' Desmogaster'' Rosa, 1890 *''Drawida ''Drawida'' is a genus of annelids belonging to the family Moniligastri ...

.''

Families

Of the four

suborder Order ( la, ordo) is one of the eight major hierarchical taxonomic ranks in Linnaean taxonomy. It is classified between family and class. In biological classification, the order is a taxonomic rank used in the classification of organisms and ...

s of Haplotaxida, two are minor lineages, monotypic at family level. Another one, the

Tubificina ''Tubificina'' is a suborder of haplotaxid annelid worms. References Protostome suborders {{Annelid-stub ...

, is sizeable and contains the aquatic worms, while the fourth, the earthworms or Lumbricina, unites the bulk of the order's families: Suborder Haplotaxina * Haplotaxidae Suborder Moniligastrina * Moniligastridae Suborder Lumbricina *

Alluroididae Alluroididae is a family of annelids belonging to the order Haplotaxida The Haplotaxida are one of two orders within the annelid subclass Oligochaeta, the other being the Lumbriculida. No real common name exists, but they are simply referre ...

Eudrilidae The Eudrilidae are a family of earthworms, mostly of Africa. One species, '' Eudrilus eugeniae'' (Kinberg, 1867), is widely distributed around the warmer parts of the world and historically cultured as the "African nightcrawler".Blakemore (2015 ...

* Glossoscolecidae *

Lumbricidae The Lumbricidae are a family of earthworms. About 33 lumbricid species have become naturalized around the world, but the bulk of the species are in the Holarctic region: from Canada (e.g. ''Bimastos lawrenceae'' on Vancouver Island) and the Uni ...

* Hormogastridae * Ailoscolidae * Lutodrilidae * Sparganophilidae * Criodrilidae * Ocnerodrilidae * Acanthodrilidae * Octochaetidae * Exxidae * Megascolecidae * Microchaetidae Suborder

Tubificina ''Tubificina'' is a suborder of haplotaxid annelid worms. References Protostome suborders {{Annelid-stub ...

Dorydrilidae Dorydrilidae is a family of annelids belonging to the order Haplotaxida The Haplotaxida are one of two orders within the annelid subclass Oligochaeta, the other being the Lumbriculida. No real common name exists, but they are simply referre ...

* Enchytraeidae * Naididae (including Tubificidae) *

Opistocystidae Opistocystidae is a family of annelids belonging to the order Haplotaxida The Haplotaxida are one of two orders within the annelid subclass Oligochaeta, the other being the Lumbriculida. No real common name exists, but they are simply refer ...

Phreodrilidae Phreodrilidae is a family of annelids belonging to the order Haplotaxida The Haplotaxida are one of two orders within the annelid subclass Oligochaeta, the other being the Lumbriculida. No real common name exists, but they are simply referr ...

Families

See also