Dugesiidae is a

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

of freshwater planarians distributed worldwide (except

Antarctica Antarctica () is Earth's southernmost and least-populated continent. Situated almost entirely south of the Antarctic Circle and surrounded by the Southern Ocean, it contains the geographic South Pole. Antarctica is the fifth-largest contine ...

). The

type genus In biological taxonomy, the type genus is the genus which defines a biological family and the root of the family name. Zoological nomenclature According to the International Code of Zoological Nomenclature, "The name-bearing type of a nominal f ...

is ''

Dugesia ''Dugesia'' (pronounced, /duˈd͡ʒiʒ(i)ə/) is a genus of dugesiid triclads that contains some common representatives of the class Turbellaria. These common flatworms are found in freshwater habitats of Africa, Eurasia, and Australia. ''Duge ...

'' Girard, 1850.Ball, I. R.: A contribution to the phylogeny and biogeography of the freshwater triclads (Platyhelminthes: Turbellaria). Biology of the Turbellaria (Edited by: Riser NW and Morse MP). New York: McGraw-Hill New York 1974, 339-401.

Description

All species of Dugesiidae live in freshwater environments and have a dorsoventrally flattened body. The head usually has a somewhat triangular shape and has two eyes (except for some subterranean eyeless species). The main differences between Dugesiidae and other freshwater planarians are related to the anatomy of the eyes and the copulatory apparatus. The eye cup in Dugesiidae is composed of several retinal cells, while in other freshwater planarians they are composed of a single cell. All freshwater planarians have an accessory organ called copulatory bursa or ''bursa copulatrix'', which is connected to the genital atrium by a canal. In Dugesiidae, the oviducts, which conduct the eggs from the ovaries to the genital atrium, open into the bursal canal, while in other freshwater planarians they open directly into the genital atrium.

Phylogeny

According to molecular analyses, Dugesiidae is the sister group of

land planarians Geoplanidae is a family of flatworms known commonly as land planarians or land flatworms. These flatworms are mainly predators of other invertebrates, which they hunt, attack and capture using physical force and the adhesive and digestive proper ...

. Phylogenetic supertree including all major triclad groups after Sluys et al., 2009: Phylogenetic subtree including five dugesiid genera after Álvarez-Presas et al., 2008:

References

{{Taxonbar, from=Q3030805 Platyhelminthes families