Turbellarian Taxonomic Database

A listing of the taxonomy of turbellarians
(formerly class Turbellaria of the phylum Platyhelminthes)

Taxonomic search (for taxon, taxonomic authority, taxonomic literature)
  Biogeography search (by location, coordinates, authority)
  History of turbellarian research (those who conducted research on turbellarians)
Acoelomorpha Ehlers, 1985
Nemertodermatida Karling, 1940
Acoela Uljanin, 1870
Ambulacraria (Echinodermata / Hemichordata)
Chordata (Vertebrata / Urochordata / Cephalochordata)
Platyhelminthes* Minot, 1876 [Hyman, 1951] / Plathelminthes Schneider, 1873 [Ehlers & Sopott-Ehlers, 1995]
Catenulida Graff, 1905
Rhabditophora Ehlers, 1985
Macrostomorpha Doe, 1986
Trepaxonemata Ehlers, 1984
Amplimatricata Egger, Lapraz, Tomiczek, Mueller, et al., 2015
Polycladida Lang, 1881 [sensu Faubel, 1983/1984]
Prorhynchida Karling, 1974
Gnosonesimida Karling, 1974
Euneoophora Laumer & Giribet, 2014
Rhabdocoela Meixner, 1925
Kalyptorhynchia Graff, 1905
Dalytyphloplanida Willems, Wallberg, Jondelius, Littlewood, Backeljau, Schockaert, Artois, 2006
Neodalyelliida Willems et al., 2006
Neotyphloplanida Willems et al., 2006
Limnotyphloplanida Van Steenkiste et al., 2013
Temnocephalida Blanchard, 1849 = Temnocephalidae Van Steenkiste et al., 2021
Thalassotyphloplanida Willems et al., 2006
Proseriata Meixner, 1938
Acentrosomata Egger, Lapraz, Tomiczek, Mueller, et al., 2015
Adiaphanida Noren & Jondelius, 2002
Tricladida Lang, 1884
Maricola Hallez, 1892
Cavernicola Sluys, 1990
Continenticola Carranza, Littlewood, Clough, Ruiz-Trillo, Baguna, & Riutort, 1998
Prolecithophora Karling, 1940
Fecampiida Rohde, Luton & Johnson, 1994
Urastomidae, Fecampiidae, Genostomatidae, Notenteridae
Bothrioneodermata Egger, Lapraz, Tomiczek, Mueller, et al., 2015
Bothrioplanida Sopott-Ehlers, 1985
Neodermata Ehlers, 1985
Monogenea - [see Monogenea on WoRMS]
Cestoda: Gyrocotylidea / Amphilinidea + Eucestoda - [see Cestoda on WoRMS]
Trematoda: Aspidogastrea + Digenea - [see Trematoda on WoRMS]

*Hierarchy for Platyhelminthes reflects Egger et al. (2015) and Laumer & Giribet (2014)

database last modified: 20 June, 2024

Cite as "Tyler S, Schilling S, Hooge M, and Bush LF (comp.) (2006-2024) Turbellarian taxonomic database. Version 2.1 http://turbellaria.umaine.edu"

About turbellarians

Traditional, pre-cladistic systems placed the flatworms in a single phylum, the Platyhelminthes, subdivided into the classes Turbellaria, Monogenea, Trematoda, and Cestoda. Turbellarians are the largely free-living flatworms---those that don't parasitize other animals---while the other classes encompass the obligate parasites, most of which live in or on the bodies of vertebrates. Turbellaria is, in particular, considered an invalid class because it is not monophyletic. (It is either paraphyletic--that is, having descendants, namely the parasitic classes, that are not classified within it [Ehlers, 1985]; or it could be polyphyletic--that is, having arisen from more than one ancestor, one for the acoels and another for catenulidans and rhabditophorans [Baguñà and Riutort, 2004; Phillipé et al., 2011]). The term "turbellarian" can still be applied to those worms that were formerly classified in the Turbellaria, but the term "Turbellaria" (specifically, the capitalized taxon name) would have to be written in quotation marks to indicate its paraphyletic status. Not all turbellarians are free-living.

In recognition of recent proposals based on molecular sequences (particularly of 18s rDNA, some Hox genes, and, most recently, fuller genomic data) the system displayed here treats the Acoelomorpha as separate from the phylum Platyhelminthes. The position and status of Acoelomorpha have been volatile in molecular-systematics studies, some claiming that it itself is paraphyletic, many claiming that it (possibly as separate taxa Acoela and Nemertodermatida) belongs near the base of the animal tree of life, as the most basal bilaterians---that is, the most primitive of any animal phylum outside of the sponges and cnidarians. Phylogenomic studies place the Acoelomorpha either within the Deuterostomia (Philippé et al., 2011) or more basally as a sister group to all other bilaterians (Hejnol et al., 2009; Cannon et al., 2016). As a deuterostome, the Acoelomorpha would be in a phylum Xenacoelomorpha that includes also the enigmatic sack-like animal Xenoturbella), and the Xenacoelomorpha is itself placed as sister group to the Ambulacraria (Ehinoderms + Hemichordata). Significantly, proposals that Acoelomorpha was the most primitive bilaterian---a controversial claim that did not make sense in terms of the morphology of acoels---are likely to be the result of statistical error (Philippé et al., 2019; Kapli & Telford, 2020). Achatz et al. (2013) comprehensively review the morphological and molecular characters that apply to the placement of the Acoela. The Platyhelminthes, as defined in all of these molecular systems, would be only distantly related to the Acoelomorpha and classified as a lophotrochozoan phylum, in a group with Annelida and Nemertea (Philippé et al., 2019).

This taxonomic database covers all turbellarian flatworms, including parasitic turbellarians. The position of the major parasitic taxa (the other classes in the traditional system), encompassed now in the taxon Neodermata, is indicated in the hierarchy here in accordance with Egger's et al. (2015) transcriptomic-phylogenomic analysis. No neodermatans, themselves, are treated here, however.

References cited

Achatz JG, Chiodin M, Salvenmoser W, Tyler S, Martinez P (2013) The Acoela: on their kind and kinships, especially with nemertodermatids and xenoturbellids (Bilateria incertae sedis). Organisms, Diversity, and Evolution. 13:267-286; DOI: 10.1007/s13127-012-0112-4 http://www.springerlink.com/content/j438837426x12815/

Baguñà J, Riutort M (2004) Molecular phylogeny of the Platyhelminthes. Can J Zool 82:168-193.

Cannon JT, Vellutini BC, Smith III J, Ronquist F, Jondelius U, Hejnol A (2016) Xenacoelomorpha is the sister group to Nephrozoa. Nature 530:89-93 doi:10.1038/nature16520.

Egger B, Lapraz F, Tomiczek B, Müller S, Dessimoz C, Girstmair J, Skunca N, Rawlinson KA, Cameron CB, Beli E, Todaro MA, Gammoudi M, Noreña C, Telford MJ (2015) A transcriptomic-phylogenomic analysis of the evolutionary relationships of flatworms. Current Biology 25, 1347-1353 http://dx.doi.org/10.1016/j.cub.2015.03.034

Ehlers U (1985) Das Phylogenetische System der Plathelminthes. Gustav Fischer, Stuttgart, New York. 317 pp

Hejnol A, Obst M, Stamatakis A, Ott M, Rouse GW, Edgecombe GD, Martinez P, Baguna J, Bailly X, Jondelius U, Wiens M, Muller WEG, Seaver E, Wheeler WC (2009) Assessing the root of bilaterian animals with scalable phylogenomic methods. Proc. R. Soc. B. 276, 4261-4270.

Kapli P, Telford MJ (2020) Topology-dependent asymmetry in systematic errors affects phylogenetic placement of Ctenophora and Xenacoelomorpha. Science Adv. 6(50): eabc5162. doi: 10.1126/sciadv.abc5162

Laumer C, Giribet G (2014) Inclusive taxon sampling suggests a single, stepwise origin of ectolecithality in Platyhelminthes. Biol J Linn Soc Lond, 111: 570-588. doi:10.1111/bij.12236

Philippé H, Brinkmann H, Copley RR, Moroz LL, Nakano H, Poustka AJ, Wallberg A, Peterson KJ, Telford MJ (2011) Acoelomorph flatworms are deuterostomes related to Xenoturbella. Nature 470(7333): 255-258 doi:10.1038/nature09676

Philippe H, Poustka AJ, Chiodin M, Hoff KJ, Dessimoz C, Tomiczek B, ..., Copley RR, Martinez P, Telford MJ (2019) Mitigating anticipated effects of systematic errors supports sister-group relationship between Xenacoelomorpha and Ambulacraria. Curr Biol 29: 1818-1826 https://doi.org/10.1016/j.cub.2019.04.009

About the taxonomic listing

Louise Bush sorting turbellarians

Data in this listing were initially compiled by Louise Bush using programs developed by Seth Tyler. Dr. Bush's last update to the database was in 1991, the year of her death. Since 1991, the database has been updated by S. Tyler, Steve Schilling, and Matt Hooge, with help from specialists on various groups of turbellarian platyhelminths, including Masaharu Kawakatsu, Ulrich Ehlers, Marco Curini-Galletti, Oleg Timoshkin, Tom Artois, Lukas Schärer.

Steve Schilling collecting geographic data

Availability of images is denoted with -symbols; these link to one or more images of mostly systematic importance. Most of those of Rhabdocoela and Proseriata were kindly provided by Tom Artois and Ernest Schockaert of Universitair Centrum, Deipenbeek, Belgium; Matt Hooge, University of Maine; and Rick Hochberg, Smithsonian Institution, Fort Pierce, FL. Images of Acoela, Prolecithophora, and other Rhabdocoela were provided by Matt Hooge.

The data pertaining to the Acoelomorpha is the most reliable, having been checked more thoroughly for accurracy in synonymy and literature citations. Notes in this section (reached with the "notes" links and the -symbols by the taxon names) are transcriptions from or images of index cards that Louise Bush maintained. They summarize references to the taxa made in the literature (up to about 1991; more recent notes are separated from Bush's with a horizontal line). Notes on groups outside the Acoelomorpha are mostly in the form of images of index cards. Steve Schilling transcribed Bush's notes and scanned the cards for this database. He is also entering biogeographical data.

Entry of data on the geographic distribution of species was supported in part by the Ocean Biogeographic Information System (OBIS). Steve Schilling is handling these data, gathering collection records of turbellarian species world-wide (both marine and freshwater). Species for which data have been entered are flagged with a "dist'n hyperlink, and clicking on this hyperlink will list those records. Maps of those collection sites can be reached using the map hyperlink and the map all distribution points at the end of each listing. (Resources we use for determining geographic coordinates of collecting sites and for drawing maps [Google Maps and Topozone] are listed separately: mapping resources.)

This is a work in progress. Copyrights for images remain with the original print publishers. Please send corrections to Seth Tyler,-->Seth Tyler, E-Mail "styler at maine dot edu"

Explanation (electronic poster) of how the databases work

See also explanation of Platyhelminthes--the nature of a controversial phylum, which includes an explanation of Acoela and its relationship to the Platyhelminthes.

Cite as "Tyler S, Schilling S, Hooge M, and Bush LF (comp.) (2006-2023) Turbellarian taxonomic database. Version 2.1 http://turbellaria.umaine.edu"

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This work is licensed under a Creative Commons License.

This material is based upon work supported by the National Science Foundation under Grant No. 0118804.