Stolidobranchia is an order of tunicates in the class Ascidiacea. The group includes both colonial and solitary animals. They are distinguished from other tunicates by the presence of folded pharyngeal baskets. This provides the etymology of their name: in ancient Greek, means the "fold" of a cloth. Stolidobranchian sea squirts are also characterized by the complete absence of an abdomen. The abdominal organs of other tunicates are instead located to one side of the pharyngeal basket in this group. Taxonomy Molgulidae Lacaze-Duthiers 1877 [Hexacrobylidae Seeliger 1906; Caesiridae] Anomopera Hartmeyer, 1923 Asajirus Kott, 1989 [Hexadactylus Monniot & Monniot 1990] Bostrichobranchus Traustedt, 1883 Eugyra Alder & Hancock, 1870 [Eugyrioides Seeliger 1907] Fungulus Herdman, 1882 Gamaster Pizon, 1896 Minipera Monniot & Monniot, 1974 Molgula Forbes, 1848 [Anurella Lacaze-Duthiers 1877; Ascopera Herdman 1881; Astropera Pizon 1898; Caesira Flemming 1822; Ctenicella Lacaze-Duthiers 1877; Cystingia MacLeay 1825; Eugyriopsis Roule 1885; Euritteria Huntsman 1922; Gymnocystis Giard 1872; Lithonephria Giard 1872; Lithonephrya Giard 1872; Meristocarpus Pizon 1899; Molgulidium Seeliger 1907; Molgulina Hartmeyer 1914; Pera Stimpson 1852; Syphonotethis Gervais 1840; Xenomolgula Ärnbäck 1931] Molguloides Huntsman, 1922 Namiella Monniot & Monniot, 1968 Oligotrema Bourne, 1903 [Gasterascidia Monniot & Monniot 1968; Hexacrobylus Sluiter 1905; Sorbera Monniot & Monniot 1974] Paramolgula Traustedt, 1835 [Stomatropa] Pareugyrioides Hartmeyer, 1914 Protomolgula Monniot, 1971 Rhizomolgula Ritter, 1901 Pyuridae Hartmeyer 1908 [Plidaeuridae] Bathypera Michaelsen, 1904 [Halomolgula Ritter 1907] Bathypyura Monniot & Monniot, 1973 Boltenia Savigny, 1816 Bolteniopsis Harant, 1927 [Liouvillea Sluiter 1929] Claudenus Kott, 1998 [Ctenicella Kott 1972] Cratostigma Monniot & Monniot, 1961 Ctenyura Van Name, 1918 Culeolus Herdman, 1881 Halocynthia Verrill, 1879 [Cynthia Savigny 1816; Holocynthia Verrill 1879; Tethyum Bohadsch 1761] Hartmeyeria Ritter, 1913 [Ectorchis Huntsman 1922] Hemistyela Millar, 1955 Herdmania Lahille, 1888 [Rhabdocynthia Herdman 1891] Heterostigma Ärnbäck-Christie-Linde, 1924 Microcosmus Heller, 1877 Paraculeolus Vinogradova, 1970 Pyura Molina, 1782 [Cynthiopsis Michaelsen 1904; Forbesella Lacaze-Duthiers & Delage 1892; Forbesia Lacaze-Duthiers & Delage 1892; Hyalocynthia Oka 1930; Paracynthia Ärnbäck 1938; Podocynthia Oka 1929; Pyuropsis Michaelsen 1912] Pyurella Monniot & Monniot, 1973 Styelidae Sluiter 1895 [Botryllidae Giard 1875] Alloeocarpa Michaelsen, 1900 Arnbackia Brewin, 1950 Asterocarpa Brewin, 1946 Bathyoncus Herdman, 1882 Bathystyeloides Seeliger, 1907 Berillia Brewin, 1952 Botryllocarpa Hartmeyer, 1909 [Protobotryllus Pizon 1908] Botrylloides Milne-Edwards, 1841 [Metrocarpa Ärnbäck-Christie-Linde 1923; Sarcobotrylloides Drasche 1883] Botryllus Gaertner, 1774 [Alcyonium Pallas 1766; Myxobotrus Oka 1931; Parabotryllus Kott 1975; Polycyclus Lamarck 1815] Chorizocarpa Michaelsen, 1904 Cnemidocarpa Huntsman, 1913 [Azygocarpa Oka 1932; Ypsilocarpa Ärnbäck 1922] Dendrodoa MacLeay, 1824 [Styelopsis Traustedt 1883] Dextrocarpa Millar, 1955 Diandrocarpa Van Name,