Ordo Haplotaxida

Brinkhurst in Brinkhurst and Jamieson, 1971

Number of families 2, with 10 genera and 33 species. In NWE, one species:
Haplotaxis gordioides (Hartmann, 1821)
Some more species are recorded from the nearby Pyrenees.

Description
Oligochaeta with sigmoid chaetae only, either simple-pointed or with small upper tooth, two or one per bundle. Testes in X and XI (or only in XI), ovaries in XII (or XII and XIII); sometimes the whole set shifted forward by one segment. Male ducts plesioporous (located in segment subsequent to corresponding testes), very short and simple, without any atria, prostate glands or penes. Spermathecae in pretesticular segments. Brinkhurst and Jamieson, 1971 defined the Order Haplotaxida sensu lato as including all aquatic and terrestrial oligochaete families except for Lumbriculidae and Moniligastridae. In this guide, Haplotaxida are treated in the narrow sense, with the families of Haplotaxidae and Tiguassidae. The most primitive group of Oligochaeta and Clitellata, apparently paraphyletic.
Burrowing in sediment.

Distribution
Cosmopolitan.

Ecology
In freshwater.

Reproduction
Sexual only. Eggs laid in cocoons.

Literature
Brinkhurst and Jamieson, 1971: 196; Jamieson, 1980: 273.

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