Metcalf, 1919
Solitary zooids
Test thin and flabby, entirely smooth (Ritteriella amboinensis, Ritteriella retracta). Body elongate and cylindrical. The number of body muscles varies from 9 to 31; usually interrupted ventrally. This interruption is barely visible in the anterior part of the body but widens toward the posterior end. Muscles frequently anastomose in the mid-dorsal region. Intestine varying from loosely coiled to longitudinally stretched. Blood-forming organ on the left side of the intestine.
Aggregate zooids
Fusiform, as in genus Salpa (Ritteriella amboinensis 1, Ritteriella retracta 1). The posterior projection is notably longer than the anterior one. Test voluminous. Six body muscles are continuous dorsally but widely separated ventrally. They are arranged as in genus Salpa but differ in the dorsal fusion of MI and MII, which extends to the lateral parts, giving the impression of only 3 fused muscles instead of 4. MIV and MV widely separated and not converging laterally. A branch of MVI surrounds the atrial opening. Embryo between MV and MVI.
Three species are recognized, two of which have been recorded from the South Atlantic Ocean, although the records of Ritteriella amboinensis are doubtful (see Sa.2 Geographic and vertical distribution).
Ritteriella amboinensis (Apstein, 1904)
Ritteriella retracta (Ritter, 1906)