Eudistoma laysani ( Sluiter, 1900 )

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 : 10

Eudistoma laysani ( Sluiter, 1900) NEW RECORD

Figure 4 A–D

All colonies with a cluster of small bright pink upright heads in life. The collected samples agree with published descriptions except for the bright pink color of the living colonies; however, F. Monniot (pers. comm.) says the colonies can occur in various colors and color alone is not a defining character. Color pale and transparent in fixative but usually with numerous very small dark pigment spots. Siphons six lobed.

#2567, colony about 3 cm across. Thoraxes of zooids orange and short; esophagus very long. Length of zooids about 1 cm. Larva as in Tokioka (1967).

#2578, on small coral rubble. Some zooids with larvae.

#2612, very small colony, only two small heads. Zooids very contracted.

#3815, several colonies collected intertidally. Color in formalin is the brown/green as described by Tokioka (1967) and Monniot C. & Monniot F. (1987). Entire abdomen is embedded in the basal sandy part. Clump of up to about 19 testis follicles in curve of gut and on dorsal side of gut. Numerous longitudinal muscles extend to posterior end of zooids from siphons; circular muscles on thorax peter out at the base of the thorax. Stomach orange, poststomach colorless, anterior intestine orange. With larvae, most advanced have three adhesive papillae and four pairs of long lateral ampullae. Largest larva about 0.8 mm.

#4630C, one small colony.

Distribution: Vietnam, Palau, Philippines, New Caledonia, Australia, Indonesia, Fiji, Banda, Thailand, China, Hawaii.

References with detailed descriptions and figures: Tokioka (1967), Senawong (1972), Millar (1975), Monniot C. & Monniot F. (1987), Meenakshi (2002), Monniot F. (2009b), Kott (1990), Monniot F. & Monniot C. (1996, 2001). Additional references: Monniot F. (1988), Zheng (1995), Abbott et al. (1997).

Figures

FIGURE 4. A–D: Eudistoma laysani. A: whole living colony 3 cm across; B: one head; C: unhatched tadpole 800 µm in length; D: one head of preserved colony. E: Eudistoma regina, part of large colony; F: Aplidium cf. grisiatum colony 1.5 cm in width; G–H: Pseudodistoma fragile. G: whole living colony 4 cm across; H: single zooid 8 mm in length, somewhat contracted. Scale bar: E, 0.4 cm.