PACIFIC TUNICATA OF U.S. NATIONAL MUSEUM 77 



27. Didemnum (Dideninuni) ternatanum (GoUsclialdl) 



Figure 24/ 



Didemnoides ternatanum Gottschaldt, 1898, p. 648, pi. 35, tig. 1. 



Didemnum ternatanum Van Name, 1918, p. 152, figs. 104-1 OG. 



Didemnum {Didemnum) ternatanum Tokioka, 1955b, p. 47, pi. 3, figs. 18-29. 



MATERIAL EXAMINED 



Philippine Isi^nds : Basilau Island ; Tundun Pasil, near lighthouse at Isabela 

 channel, 1 fathom ; W. R. Taylor, coll., January 1941. One specimen 3.4 X 2.5 

 mm. in extent and 2 mm. thick, with .52 branchial apertures on the surface 

 (USNM 11686).— Basilan I.sland ; Punta Natangol, W. R. Taylor, sta. 31. one 

 small, elongated colony 2X8 mm. in extent (USNM 11666). 



Pai.au Islands: West end of Koror Island, GVF sta. 12; 4 colonies (USNM 

 11400).— West end of Koror Island, GVF sta. 16; 33 colonies (USNM 11404).— 

 Southern end of Urukthapel Island, GVF sta. 67; 1 colony (USNM 11420).— 

 Iwayama Bay, mouth of Oyster Pass, GVF sta. 236A ; many colonies (USNM 

 11427).— Ngerkuid, west of Eil Malk, GVF sta. 261; 12 colonies (USNM 11398). 



Description. — Many colonies from the Palau Islands and three 

 small pieces from the Philippine Islands were examined. They were 

 attached to fragments of reef corals, eelgrasses, HaUineda^ and algae 

 of Corallinaceae. They are roughly conical, hemispherical, or even 

 spherical in some small colonies, the largest is 41 mm. at the widest 

 part and 38 mm. in height (USNM 11420, the Palau Islands) . Com- 

 mon cloacal aperture opens at apex of colony and may reach 4 mm. in 

 long diameter. Axial core very soft and zooids are arranged in a 

 thin surface layer, consequently the colony is somewhat soft in con- 

 sistency. Preserved specimens are whitish, light brownish, reddish 

 brown, dark grayish, or blackish; usually most dark pigmented in 

 distal part of colony surrounding conmion cloacal aperture, but basal 

 half is whitish, grayish white or rather translucent. Common cloacal 

 aperture and (in many cases) brancliial apertures are also fringed 

 densely with white spicules. On some colonies, spicules rather 

 sparse, especially in basal portion; in such specimens, when alive, 

 greenish tint of zoochlorellae contained in lacunae system is seen 

 through the test (the preservative is usually colored green by dissolv- 

 ing the chlorophyll of zooclilorelhie). Spicules small, of candiduTn- 

 type; usually 16-20/i, in diameter, may be only 10-1 5/a in some col- 

 onies, but exceptionally up to 20-J33/X in a specimen from the Philip- 

 pines (USNM 11G6()). Rays short and very numerous. Branchial 

 apertures 6-lobed, stigmatal rows four. One testicular follicle, proxi- 

 mal part of vas deferens coils 51/^ to G times. Situation of respec- 

 tive parts of the alimentary canal quite the same as in common species 

 of the genus Didemnum. 



Remarks. — Small colonics of this species closely resemble those of 

 Lissoclinum pul/vinum (Tokioka) which also contains zoochlorellae in 

 the lacuna sy.stem. However, the spicules are distinctly of the candi- 



