CORELLIDAE Herdman, 1882

Kott, Patricia, 2009, Taxonomic revision of Ascidiacea (Tunicata) from the upper continental slope off north-western Australia, Journal of Natural History 43 (31 - 32), pp. 1947-1986 : 1970-1971

Family CORELLIDAE Herdman, 1882

Type genus: Corella Alder, 1870 .

The family contains phlebobranch ascidians with rows of coiled stigmata held in place by radial parastigmatic vessels and crossed by internal longitudinal branchial vessels; long pointed dorsal languets; a narrow gut loop around the postero-dorsal corner of the body to the right of the mid line; and gonads in the pole of the gut loop consisting of masses of minute testis follicles that mingle with the ovarian tubules and spread over the wall of the gut.

The family is distinguished from Agneziidae (which also has rows of coiled stigmata) by the location of the gut loop to the right (rather than the left) of the midline and the interruption of the internal longitudinal branchial vessels leaving simple or bifid papillae. Rhodosomatidae , sometimes considered a sub-family of the Corellidae , also has the gut loop on the right side of the body, but straight rather than coiled stigmata. The family may be related to the Ciallusiidae , having similar dorsal languets, although the latter family lacks the spiral stigmata and the gut is on the left side of the body.

In addition to the type genus, the family Corellidae contains some little known genera from the northern hemisphere, including the northern Pacific, Behring Sea and other Arctic locations, the best known being Chelyosoma with horny scales formimg an oral disk around the apertures. Other Arctic species Corelloides and Corellopsis are distinguished by the interruption and reduction of the internal longitudinal vessels. The only genera known from the southern hemisphere are the type, Corella and Corynascidia Herdman, 1880 ( Van Name 1945; Monniot C and Monniot F 1991). Corynascidia was thought to have larger meshes and more coils of each stigma than Corella , but many species of Corella have similar large meshes and numerous coils of the stigma ( Van Name 1945). A stalk from the antero-ventral part of the body is the only consistent feature of Corynascidia that does not occur in Corella . It is difficult to understand the proposal ( Monniot C and Monniot F 1991) that, as a consequence of the origin of the stalk from the antero-ventral corner of the body, the position of the gut loop in Corynascidia is actually posterior to the body rather than to the right of the midline.

The genus Corynascidia is known from C. suhmi Herdman, 1882 (from the southern Indian, Pacific and Atlantic Oceans and the North Atlantic ( Sanamyan KE and Sanamyan NP 2005)), C. herdmani Ritter, 1913 from the north-eastern Pacific and C. lambertae and C.mironvi both described from the South Atlantic at 1400 m and 5120 m respectively by K.E. Sanamyan and N.P. Sanamyan (2002).

Pterygascidia inversa Monniot C. and F. 1991 has, as do species of the genus Corynascidia (see C. suhmi: Sanamyan K and N, 2005), a narrow stalk arising antero-ventrally, the pharyngeal wall, a caecum reduced to an open mesh of transverse sinuses with vertical papillae supporting longitudinal sinuses, a short eggshaped stomach with parallel rounded folds, dorsal lobes on the anal rim and characteristic short body muscles, including the two bundles of short transverse bands, one ventral and one dorsal to the atrial aperture (across the distal part of the rectum). The fine radial vessels that stabilize the traces of the branchial wall and the coils of the stigmata may be degenerate in this specimen, which very probably is a species of Corynascidia .

Other species originally assigned to Corynascidia that appear to be more properly regarded as Corella spp. are C. sedens ( Sluiter, 1904) from Indonesia and the possibly conspecific (see later) C. alata (Monniot C. and F., 1991) from New Caledonia and C. translucida (Monniot C., 1969) from the north-eastern Atlantic (distinguished by a complex mesh of muscles on the left side of the body).

The genus Corella is the most speciose in this family and species (in addition to the three probable synonyms originally referred to Corynascidia ) are known from the Arctic, the north-eastern Atlantic, the tropical western Atlantic, the north-eastern Pacific, Japan, the tropical western Pacific (see later), temperate waters of the southern hemisphere and the Sub-antarctic and Antarctic ( Van Name 1945; Tokioka 1967; Berrill 1950).