Scientific Name and Authority

Ascidia sydneiensis   Stimpson, 1855


Ascidia sydneiensis is a large solitary tunicate which can vary in color, and may be white, cream, yellow, orange, red, or wine-colored. The tunic itself is translucent and the color is caused by pigmentation on the body wall. It has an elongate body shape that tapers into a long oral siphon with 35-200+ oral tentacles. A shorter atrial siphon projects off the left side of the body. The oral siphon typically has seven or eight lobes and the atrial siphon has six. On both siphons, the lobes are separated by indented margins, or long projections and there is a dark spot (often red) between lobes (Bonnet and Rocha, 2011). The tunic is finely wrinkled with minute translucent hairs and can be encrusted with detritus, algae and other invertebrates. When the tunic is removed the muscles on the oral and atrial siphons are conspicuous. The siphons have prominent circular muscle bands and some longitudinal bands. On the right side, 'there is a wide border of short, stout muscle bands extending inward from the margin for a varying distance. They lie for the most part parallel to each other and at right angles to the margin, but curve and cross each other irregularly to a slight extent.' (Van Name 1945). Muscle bands are largely absent from the left side of the body. The large S-shaped digestive tract covers the left side of the body. The largest Caribbean specimen examined by Van Name (1945) was 53 mm long and 27 mm wide, similar to that described by Nishikawa (1991), but Van Name noted that larger specimens had been reported from the Eastern Hemisphere (Van Name 1945; Eldredge and Smith 2001; Nishikawa 1991).

Taxonomic Classification:

Kingdom: Animalia
Phylum: Chordata
Subphylum: Tunicata
Class: Ascidiacea
Order: Phlebobranchia
Family: Ascidiidae
Genus: Ascidia
Species: sydneiensis


Ascidia canaliculata (Heller, 1878)

Ascidia diplozoon (Sluiter, 1887)

Ascidia incerta (Herdman, 1889)

Ascidia pyriformis (Herdman, 1880)

Phallusia longitubis (Traustedt, 1882)

Phallusia sydneiensis (Stimpson, 1855)

Ascidia rudis (Schmelz, 1879)

Phallusia pyriformis (Traustedt, 1885)

Ascidia limosa (Sluiter, 1887)

Ascidia divisa (Sluiter, 1898)

Ascidia bisulca (Sluiter, 1904)

Phallusia canaliculata (Hartmeyer, 1909)

Ascidia longitubis (Sluiter, 1898)

Ascidia donnani (Herdman, 1906)

Potentially Misidentified Species:

Ascidia canaliculata

Cape of Good Hope, South Africa. This species had been listed as a synonym, (Van Name 1945; Kott 1985; Kott 2005). However, Rosana da Rocha (personal communication 2012) considers it a valid species, based on dissertation research by Nadia Bonnet.