On the Previously Undescribed Aggregate Form of the Pelagic 
Tunicate Ritteriella picteti (Apstein) (1904)^ 
Leo D. Berner2 
During March, April, and May, 1949, 
over 400 specimens of 'Ritteriella picteti were 
taken off the west coast of the United 
States and Baja California in the net hauls 
taken by the Scripps Institution of Oceano- 
graphy in conjunction with the California Co- 
operative Research Program. This is its first 
reported occurrence in the eastern Pacific 
Ocean and in large numbers. In this material 
the solitary form and the undescribed aggre- 
gate form are both represented. The original 
recognition of the aggregate form was based 
on specimens that contained embryos of the 
solitary form which were mature enough to 
possess their characteristic diagnostic fea- 
tures. Five individuals of the aggregate gen- 
eration have been deposited in the United 
States National Museum, under number 11170. 
I wish to express my appreciation to Dr. 
Martin Johnson for his valuable assistance in 
the preparation of this manuscript. 
In the past Ritteriella picteti has been con- 
sidered a rare species by all workers on the 
Thaliacea. Apstein (1904: 655) described the 
species from a single specimen taken off Am- 
boina, Dutch East Indies. He again found the 
species in the Tiefsee Expedition material 
(1906^.' 252), listing two specimens, but ap- 
pears to have confused it with R. amboinensis, 
so the number may be higher. From the 
Deutsche-Siidpolar Expedition, Apstein 
(I906A 168) reported three specimens of R. 
picteti. Ritter (I906: 1-5) took one specimen 
from Sugura Bay, Japan, which he described 
as a new species, Cyclosalpa retracta. Ihle (I9IO: 
43-46) reported two specimens from the Si- 
boga collections, and Sewell (1926) reported 
^ Contribution from Scripps Institution of Oceano- 
graphy New Series No. 686. Manuscript received June 
12 , 1953 . 
2 Scripps Institution of Oceanography, University 
of California, La Jolla, California. 
two specimens from the Indian Ocean collec- 
tions he examined. Komai (1932: 64-69) and 
Thompson (1948: 124-126) each reported one 
specimen from their collections. Thus more 
than 13 specimens, all of the solitary form, 
were reported in nearly 50 years of investiga- 
tion. Thompson (1948: 125) suggested that 
he may have found the aggregate form of the 
species, but from his description it appears 
that he must have been looking at a very 
young individual or at another species. 
Ritteriella picteti (Apstein) (1904) 
Cyclosalpa retracta Ritter, 1906 
Salpa amhoinensis Apstein, 1906^/ 
[non] S. amhoinensis Apstein, 1904 
Salpa picteti Apstein, 1906^ 
Salpa picteti Apstein, 1906^ 
Salpa retracta Ihle, 1910 
Salpa picteti Ihle, 1910 
Salpa picteti Ihle, 1912 
Salpa {Ritter ia) picteti Metcalf, 1918 
Salpa {Ritteria) retracta Metcalf, 1918 
Salpa {Ritteriella) picteti Metcalf, 1919 
Salpa {Ritteriella) retracta Metcalf, 1919 
Salpa {Ritteria) picteti Sewell, 1926. 
Salpa {Ritteriella) picteti Komai, 1932. 
Ritteriella picteti Ihle, 1935 
Ritteriella picteti Thompson, 1948 
DESCRIPTION OF AGGREGATE FORM 
Body: (Eig. 1) The body is ovoid, with 
anterior and posterior - processes which are 
usually short. In dorsal view R. picteti is quite 
similar in appearance to R. amhoinensis, Salpa 
maxima, and S. fusiformis. The atrial opening 
is dorsally placed. The test is soft, often col- 
lecting debris from the sample, thus making 
the details of the animals difficult to see. The 
mature specimens examined have ranged in 
size from 9 to 35 millimeters, excluding the 
processes. 
121 
