Aplousobranchia
Introduction '''Aplousobranchia''' is an order of sea squirts in the class Ascidiacea, first described by Fernando Lahille in 1886.They are colonial animals, and are distinguished from other sea squirts by the presence of relatively simple pharyngeal baskets. This provides the etymology of their name: in ancient greek,  () means "simple". The posterior part of the abdomen contains the heart and gonads, and is typically larger than in other sea squirts.
Taxonomy Order '''Aplousobranchia'''* Family '''Clavelinidae''' Forbes & Hanley 1848 Pycnoclavellidae Kott 1990**''Clavelina'' Savigny 1816 ''Bradiclavella'' Zirpolo 1925; ''Chondrostachys'' Macdonald 1858; ''Dendroclavella'' Oka 1927; ''Podoclavella'' Herdman 1890; ''Rhodozona'' Van Name 1902; ''Stereoclavella'' Herdman 1890; ''Synclavella'' Caullery 1900**''Euclavella'' Kott 1990**''Nephtheis'' Gould 1856 ''Oxycorynia'' Drasche 1882**''Pycnoclavella'' Garstang 1891 ''Archiascidia'' Julin 1904* Family '''Diazonidae''' Garstang 1891**''Diazona'' Savigny 1816 ''Aphanibranchion'' Oka 1906; ''Syntethys'' Forbes & Goodsir 1851; ''Diagonum'' Troschel 1842; ''Diagoma'' Wade 1842** ''Pseudodiazona'' Millar 1963 ''Patridium'' Kott 1975** ''Pseudorhopalaea'' Millar 1975** ''Rhopalaea'' Philippi 1843 ''Rhopalona'' Roule 1886; ''Rhopalopsis'' Herdman 1890** ''Tylobranchion'' Herdman 1886* Family '''Didemnidae''' Giard 1872 Diplosominae Giard 1872**''Atriolum'' Kott 1983**''Clitella'' Kott 2001**''Coelocormus'' Herdman 1886**''Didemnum'' Savigny 1816 ''Didemnoides'' Drasche 1883; ''Diplosomoides'' Herdman 1886 non Lahille 1890; ''Hypurgon'' Sollas 1903; ''Leptoclinum'' Milne-Edwards 1842; ''Sarcodidemnoides'' Oka & Willey 1892; ''Tetradidemnum'' Della Valle 1881**''Diplosoma'' Macdonald 1859 ''Arenadiplosoma'' Menker & Ax 1970;  ''Astellium'' Giard 1872; ''Lioclinum'' Verrill 1871; ''Pseudodidemnum'' Giard 1872; ''Pseudodiplosoma''**''Leptoclinides'' Bjerkan 1905 ''Askonides'' Kott 1962**''Lissoclinum'' Verrill 1871 ''Diplosomoides'' Lahille 1890 non Herdman 1886; ''Echinoclinum'' Van Name 1902; ''Polysoma'' Kott 1983**''Polysyncraton'' Nott 1892**''Trididemnum'' Della Valle 1881 ''Didemnoides'' Lahille 1890 non Drasche 1884; ''Didemnopsis'' Hartmeyer 1903* Family '''Euherdmaniidae''' Ritter 1904**''Euherdmania'' Ritter 1904 ''Herdmania'' Ritter 1903 non Lahille 1888* Family '''Holozoidae''' Berrill 1950**''Colella'' Herdman 1886 ''nomen nudum'' ** ''Distaplia'' Della Valle 1881 ''Celulophana''; ''Holozoa'' Lesson 1832; ''Julinia'' Calman 1894; ''Leptobotrylloides'' Oka 1927** ''Hypsistozoa'' Brewin 1953** ''Hypodistoma'' Tokioka 1967** ''Neodistoma'' Kott 1990** ''Polydistoma'' Kott 1990** ''Protoholozoa'' Kott 1969** ''Pseudoplacentela'' Sanamyan 1993** ''Sycozoa'' Lesson 1832 ''Cyathocormus'' Oka 1913** ''Sigillina'' Savigny 1816 ''Atapozoa'' Brewin 1946; ''Atopozoa'' Brewin 1956; ''Hyperiodistoma'' Michaelsen 1930* Family '''Placentelidae''' Kott 1992**''Placentela'' Redikorzev 1913 ''Homoedistoma'' Redikorzev 1927; ''Sigillinaria'' Oka 1933* Family '''Polycitoridae''' Michaelsen 1904**''Archidistoma'' Garstang 1891** ''Brevicollus'' Kott 1990** ''Cystodytes'' Drasche 1884** ''Eucoelium'' Savigny 1816** ''Eudistoma'' Caullery 1909 ''Distoma'' Savigny 1816 non Retzius 1786; ''Paessleria'' Michaelsen 1909** ''Exostoma'' Kott 1990** ''Millarus'' Monniot & Monniot 1988** ''Polycitor'' Renier 1804 ''Paradistoma'' Caullery 1909; ''Tetrazona'' Michaelsen 1930** ''Polycitorella'' Michaelsen 1924** ''Rhombifera'' Peres 1956 non Barrande 1867* Family '''Polyclinidae''' Milne-Edwards 1841 Synoicidae**''Aplidiopsis'' Lahille 1890**''Aplidium '' Savigny 1816 ''Haploidium'' Agassiz 1846; ''Amaroecium'' Milne-Edwards 1841; ''Circinalium'' Giard 1872; ''Fragarium'' Giard 1872; ''Heterotrema'' Fiedler 1889; ''Parascidia'' Milne- Edwards 1841; ''Polyclinoides'' Drasche 1883; ''Sidnyum'' Savigny 1816** ''Morchellioides'' Herdman, 1886** ''Morchellium'' Giard 1872** ''Neodictyon'' Sanamyan 1988** ''Polyclinella'' Harant 1931** ''Polyclinum'' Savigny 1816 ''Glossophorum'' Lahille 1816** ''Sidneioides'' Kesteven 1909** ''Synoicum'' Phipps 1774 ''Atopogaster'' Herdman 1886; ''Lissamaroucium'' Sluiter 1906; ''Macroclinum'' Verrill 1871; ''Polyclinopsis'' Gottschaldt 1894; ''Psammaplidium'' Herdman 1886; ''Glossoforum'' Lahille 1886* Family '''Protopolyclinidae''' Kott 1992**''Condominium'' Kott 1992** ''Monniotus'' Millar 1988** ''Protopolyclinum'' Millar 1960* Family '''Pseudodistomidae''' Harant 1931** ''Anadistoma'' Kott 1992** ''Citorclinum'' Monniot & Millar 1988** ''Pseudodistoma'' Michaelsen 1924* Family '''Ritterellidae''' Kott 1992**''Dumus'' Brewin, 1952**''Pharyngodictyon'' Herdman 1886**''Ritterella'' Harant 1931* Family '''Stomozoidae''' Kott 1990**''Stomozoa'' Kott 1957* Family '''Vitrumidae''' Kott 2009** ''Vitrum'' Kott 2009
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