Ascidia gemmata Sluiter, 1895

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 : 13

Ascidia gemmata Sluiter, 1895

Figure 5 C, D

Usually the siphons are red striped, with some additional red on both sides of endostyle and prebranchial area; color fades somewhat in formalin. Dense network of tunic blood vessels is usually visible exteriorly. In large older specimens the tunic becomes thick, cartilaginous, and yellowish except the red striped branchial siphon. The atrial siphon is usually in the posterior quarter of the body, sometimes almost at the posterior end of the body. There are numerous long dense filiform oral tentacles. The anterior rectum is usually swollen, narrowing to the anus. The antero-posteriorly flattened branchial papillae, shape of dorsal tubercle, number of stigmata per mesh and other characters all agree with published descriptions.

#0154D, one small, 2 cm long. About 50 oral tentacles. The prepharyngeal band is wide, the groove shallow with the tubercle, sparsely papillated, the papillae very tiny.

#1228B, large, 7.9 cm in length in the tunic, 7.2 cm long out of tunic. Oral siphon with eight lobes. Dorsal tubercle slightly elongated U with inrolled ends directed anteriorly. Dorsal ganglion at top of gut loop, 2 cm from the dorsal tubercle. A few large and numerous small unidentified amphipods in the branchial sac.

#2575, length 2.5 cm. With amphipods and a parasitic copepod. Oral siphon with ten lobes; rectum not distended. Also a small ascidiid, 7.5mm long out of tunic, attached by entire left side, the left side tunic very thin.

#4631, juvenile; body out of tunic 1.6 cm in length. Rectum only somewhat enlarged.

Widely distributed and common in the tropical west Pacific: Palau, Australia, New Caledonia, Indonesia, China, Singapore, Taiwan, Bali, Ponape, Majuro, Sea of Japan, Guam, Panama (Pacific side, a dubious identification by Bonnet et al. 2013).

Detailed references with figures: Tokioka (1950), Kott (1985), Monniot C. (1991a), Nishikawa (1991), Monniot F. & Monniot C. (2001, 2008), Lee et al. (2013). Other references: Nishikawa (1984, 1986), Zheng (1995), Sanamyan (1998, a questionable identification from the NW Pacific), Lambert (2003), Lee et al. (2016).

Figures

FIGURE 5. A, B: Ascidia sydneiensis about 1.5 cm in length. A: left side in tunic; B: closeup of a few clear tunic tubercles. C, D: Ascidia gemmata 7.9 cm in length in tunic (C) and left side, 7.2 cm long with tunic removed (D); E–G: Phallusia arabica. E: three individuals, largest 5.5 cm in length; F: left side of another individual 2.9 cm in length out of tunic; G: closeup of tunic blood vessels.