Ascidia interrupta Heller, 1978

Bonnet, Nadia Y. K. & Rocha, Rosana M., 2011, The family Ascidiidae Herdman (Tunicata: Ascidiacea) in Bocas del Toro, Panama. Description of six new species, Zootaxa 2864, pp. 1-33 : 14-16

Ascidia interrupta Heller, 1978

( Fig. 9 )

Material examined. DZUP ASC 80—1 ind.; Galleta floating dock; 1.0 m; 06/i/2009. DZUP ASC 81—1 ind.; Galleta Station; 1.0 m, coral reef; 06/i/2009. DZUP ASC 82—1 ind.; Casa Blanca; 0.5 m, on PVC recruitment plate; 26/iii/2009. DZUP ASC 84—1 ind.; Sachen; 11/vi/2009. DZUP ASC 73—5 ind.; STRI dock; 22/viii/2006; DZUP ASC 78—1 ind.; STRI dock; 0.5 m, on aluminum plate; 20/x/2008; DZUP ASC 83—2 ind.; STRI dock; 1.5 m; 10/ iv/2009. DZUP ASC 79—1 ind.; Marina; 0.5 m, concrete floats; 12/xii/2008. DZUP ASC 68—1 ind.; Punta Caracol; 1.0–2.0 m, coral reef; 05/viii/2003. DZUP ASC 75—1 ind.; Baía Honda; 0.5 m, mangrove roots; 23/viii/2006.

DZUP ASC 26—1 ind.; Solarte; 0.5 m, mangrove roots; 04/viii/2003; DZUP ASC 70—1 ind.; Solarte; 0.5 m, mangrove roots; 15/viii/2006; DZUP ASC 74—1 ind.; Solarte; 0.5 m, mangrove roots; 23/viii/2006. DZUP ASC 86—1 ind.; Bastimentos island; 0.5 m, on PVC recruitment plates; 09/vii/2009. DZUP ASC 76—2 ind.; Crawl Cay; 25/ viii/2006; DZUP ASC 77—1 ind.; 2.0 m, coral reef; 20/x/2008. DZUP ASC 69—1 ind.; Pastores island; 0.5 m, coral reef; 10/viii/2003; DZUP ASC 72—5 ind.; Pastores island; 1.0–2.0 m, coral reef; 17/viii/2006; DZUP ASC 85—6 ind.; Pastores island; 13/vi/2009. DZUP ASC 25—2 ind.; San Cristobal island; 0.5 m, mangrove roots; 12/viii/2003. DZUP ASC 28—1 ind.; Bocatorito Bay; 0.5 m, mangrove roots; 12/viii/2003. DZUP ASC 71—1 ind.; City; 15/viii/2006.

Individuals (to 15.0 cm, usually 5.0–10.0 cm) attach to mangrove prop roots by the posterior or the entire left side. The wide-open oral siphon with white radial lines is diagnostic in the field and the general color of the animals ranges from dark green to gray or black, but may also be yellow. The tunic is 2.0–5.0 mm thick, beige, transparent, wrinkled in some specimens. Hemispheric projections are characteristic and mostly around the siphons and on the right side, although a very few animals lack these projections. Tunic vessels are conspicuous and branched in some individuals, especially around the siphons; vessels are black in live and recently-fixed animals but fade with long term fixation.

The oral siphon is apical, variable in length (1.0– 3.5 cm); the atrial siphon (~ 1.0 cm) is in the mid-dorsal line or displaced somewhat posteriorly. Both siphons have 8–10 smooth lobes in young animals (2.0–4.0 cm long) and 14–16 in large adults; there is a dark spot between each lobe.

The body wall is opaque, brown or dark green, sometimes colorless; the siphons are usually darker than the rest of the body. Musculature on the right side comprises a net of 0.15 mm thick fibers. On the left side, the longitudinal muscles from the oral siphon are short (when they are long, never reach the intestinal loop) and a band of short parallel transverse fibers are found on the dorsal margin. The number of oral tentacles ranges between 50–140, very slender and densely packed on a thin muscular ring. Tentacles may be missing from part of the ring in some individuals. The large space between the tentacles and the prepharyngeal groove has many minute papillae. The anterior lamina of the prepharyngeal groove is usually wider, occasionally with long filiform projections. The prepharyngeal groove surrounds the dorsal tubercle forming a shallow U-shaped area. The dorsal tubercle is slightly protruding, with a U-shaped aperture, sometimes with spiraled horns; in very large animals it may become more complex with numerous irregular apertures. The neural ganglion is mid-way between the circle of tentacles and the atrial siphon, usually close to the dorsal tubercle. The primary papillae are long, laterally flattened, bi- or trilobed, with one lateral protrusion on each side. Intermediate papillae are very rare. In some animals the dorsal lamina has small projections on the right side, just before and near the esophageal aperture. The complete longitudinal vessels are 40–80 on each side, fewer on the left.

The alimentary canal occupies half or more of the left side, with an oval folded stomach (11–16 internal folds), dilation of the rectum forms a large pouch and the anus has a smooth rim. Renal accumulation vesicles are a few transparent spheres on the stomach.

Externally viewed, the cauliflower-shaped ovary is brown or dark brown within the primary loop of the intestine. The testicle comprises small, ramified follicles, on both primary and secondary intestinal loops in mature animals, inside the primary loop only in immature animals; in large animals the testis may form many patches viewed both externally and from within the atrial cavity.

Remarks. In Bocas del Toro, A. curvata and A. interrupta are sympatric in calm waters on mangrove roots, in contrast to Guadeloupe, where they are not found in this habitat ( Monniot 1983). Ascidia interrupta can be confused with A. sydneiensis because of the large dilation of the intestine and long siphon, but musculature on the right side and tunic thickness and consistency are very different. Ascidia interrupta is known from 12 locations in the Caribbean ( Van Name 1945; Millar 1962; Monniot 1983; Goodbody 1984a, 1984b, 2000, 2003; Rocha et al. 2005) as well as in northeastern Brazil ( Monniot 1969-70) and Congo ( Millar 1960).

Figures

FIGURE 9. Ascidia interrupta Heller, 1878. A. Animals in the field. B. Right side of body (without tunic). C. Left side of body (without tunic). Scale bar: B, C = 1.0 cm.