Dugesiidae

{{Automatic taxobox

| image = Girardia and Dugesia.jpg

| image_caption = Girardia sp. (top) and Dugesia sp. (down)

| taxon = Dugesiidae

| authority = Ball, 1974{{cite book |last1=Ball |first1=Ian R. |editor1-last=Riser |editor1-first=Nathan W. |editor2-last=Morse |editor2-first=M. Patricia |title=Biology of the Turbellaria |date=1974 |publisher=McGraw-Hill |location=New York |isbn=0-07-052947-7 |pages=339–401 |chapter=A Contribution to the Phylogeny and Biogeography of the Freshwater Triclads (Platyhelminthes: Turbellaria)}}

| subdivision_ranks = Genera

| subdivision_ref = {{Cite journal |last1=Sluys |first1=R. |last2=Solà |first2=E. |last3=Gritzalis |first3=K. |last4=Vila-Farré |first4=M. |last5=Mateos |first5=E. |last6=Riutort |first6=M. |doi=10.1111/zoj.12077 |title=Integrative delineation of species of Mediterranean freshwater planarians (Platyhelminthes: Tricladida: Dugesiidae) |journal=Zoological Journal of the Linnean Society |volume=169 |issue=3 |pages=523 |year=2013|doi-access=free }}

| type_genus=Dugesia

| type_genus_authority = Girard, 1850

| subdivision =

| }}

Dugesiidae is a family of freshwater planarians distributed worldwide (except Antarctica). The type genus is Dugesia Girard, 1850.{{rp|350}}

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.{{Cite journal |last1=Álvarez-Presas |first1=M. |last2=Baguñà |first2=J. |last3=Riutort |first3=M. |doi=10.1016/j.ympev.2008.01.032 |title=Molecular phylogeny of land and freshwater planarians (Tricladida, Platyhelminthes): From freshwater to land and back |journal=Molecular Phylogenetics and Evolution |volume=47 |issue=2 |pages=555–568 |year=2008 |pmid=18359250}}

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.{{cite journal |last1=Vries |first1=Elizabeth J. |last2=Sluys |first2=Ronald |title=Phylogenetic relationships of the genus Dugesia (Platyhelminthes, Tricladida, Paludicola) |journal=Journal of Zoology |volume=223 |issue=1 |year=1991 |pages=103–116 |issn=0952-8369 |doi=10.1111/j.1469-7998.1991.tb04752.x}}

Phylogeny

According to molecular analyses, Dugesiidae is the sister group of land planarians.{{Cite journal |last1=Carranza |first1=S. |last2=Littlewood |first2=D. T.| last3=Clough |first3=K. A. |last4=Ruiz-Trillo |first4=I. |last5=Baguñà |first5=J. |last6=Riutort |first6=M. |doi=10.1098/rspb.1998.0341 |title=A robust molecular phylogeny of the Tricladida (Platyhelminthes: Seriata) with a discussion on morphological synapomorphies |journal=Proceedings of the Royal Society B: Biological Sciences |volume=265 |issue=1396 |pages=631–640 |year=1998 |pmid=9881470 |pmc=1689013}}

Phylogenetic supertree including all major triclad groups after Sluys et al., 2009:{{Cite journal |last1=Sluys |first1=R. |last2=Kawakatsu |first2=M. |last3=Riutort |first3=M. |last4=Baguñà |first4=J. |title=A new higher classification of planarian flatworms (Platyhelminthes, Tricladida) |doi=10.1080/00222930902741669 |journal=Journal of Natural History |volume=43 |issue=29–30 |pages=1763–1777 |year=2009}}

{{clade| style=font-size:100%;line-height:80%

|label1=Tricladida

|1={{Clade

|1=Maricola

|2={{Clade

|1=Cavernicola

|label2=Continenticola

|2={{Clade

|label1=Planarioidea

|1={{Clade

|1=Planariidae

|2={{Clade