Eudistoma amplum ( Sluiter, 1909 )

Lambert, Gretchen, Lee, Serina Siew-Chen & Teo, Serena Lay-Ming, 2021, Ascidians collected during the 2013 Singapore Strait International Marine Biodiversity Workshop, Zootaxa 4933 (1), pp. 1-38 : 8-10

Eudistoma amplum ( Sluiter, 1909) NEW RECORD

Figure 3 D–G

#1161, colony 2.5 cm across the top, 1.2 cm thick. Light brown on outside, very green internally ( Fig. 3F ). Zooids about 8 mm in length ( Fig. 3G ).

#1203, colony pale pinkish tan, 47 mm long x 25 mm wide x 9 mm thick. Largest zooid slightly contracted, 11 mm long, with long atrial siphon.

#3787, large flat-topped tan cushion 5.1 x 4.2 cm in largest direction, about 1 cm thick, with green patches on the surface in life, similar to photo in Monniot F. (2010). Tunic completely densely embedded with sand grains and small rubble including coral fragments. Patches of clear tunic are still green after fixation. Internally there are clear green vesicles. Zooids contracted, about 6 mm long, some with larvae. Zooidal systems are more obscure than described in some monographs, perhaps due to contraction.

#3790, cushion 6 cm across in longest direction, up to 1 cm thick. Well defined systems of zooids ( Fig. 3D, E ). Smooth surface but internally tunic is full of sand and small coral debris and many spherical green globules.

#3791, two large flat-topped tan colonies, cushion-shaped. Circular zooid systems very obvious on the surface of most of the colony, though adjacent areas more obscure as in 3787 above. No green patches on surface or internally, so no clear green vesicles internally. Largest colony about 8 cm in largest dimension, smaller one about 4.5 cm. Longest zooid 6 mm.

#3860, small brown colony 1.2 cm thick x 1 cm wide. Columnar, top slightly concave. Not green, but with scattered dark reddish brown pigment granules in tunic in fixed specimen. Tunic transparent but opaque because of the granules.

#3868, brown smooth colony with short slender stalk. 3.5 cm wide x 2.4 cm tall. Tunic full of debris, fecal pellets, various granules but not green. Oval systems obvious. No larvae.

Distribution: widely distributed in the tropical west Pacific: Palau, Papua New Guinea, Philippines, Truk, Ponape, Majuro, Micronesia, Indonesia, Vietnam, Australia.

References with detailed descriptions and figures: Tokioka (1950), Millar (1975), Kott (1990), Monniot F. & Monniot C. (1996). Additional references: Tokioka (1967), Nishikawa (1984), Kott (2003), Monniot F. & Monniot C. (2001), Monniot F. (2010, figure with very brief description).

Figures

FIGURE 3. A: Distaplia micropnoa, 2 cm in height; B: Distaplia regina preserved colony 8 cm across; C: D. regina unhatched tadpole 2 mm in length; D, E: Eudistoma amplum colony 6 cm across; F, G: E. amplum different colony 2.5 cm across. F: slice through entire colony; G: single zooid 8 mm in length.