Ascidia bocatorensis, Bonnet, Nadia Y. K. & Rocha, Rosana M., 2011

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 : 4-7

Ascidia bocatorensis sp. nov.

( Figs 2–3 )

Material examined. Holotype: MZUSP 00015—1 ind.; City; 1.0 m, on polyethylene recruitment plates; 12/vii/ 2009.

Paratypes: DZUP ASC 144—1 ind.; Marina; 1.0 m, on recruitment plates; 05/iii/2009; DZUP ASC 147—1 ind.; Marina; 16/vi/2009. DZUP ASC 145—2 ind.; City; 0.5 m, on recruitment plates; 29/iii/2009; DZUP ASC 146—1 ind.; City; 21/v/2009; MZUSP 00016—2 ind.; City; 1.0 m, on recruitment plates; 12/vii/2009. DZUP ASC 143—1 ind.; Solarte; 23/viii/2006.

Etymology. The name is in reference to the type locality.

Diagnosis. Orange vessels in the tunic in life; pharynx with 7–10 stigmata per mesh; 9–17 internal folds in the stomach; ovary lobed and within both intestinal loops.

The animals are fixed to the substrate on the left side of the body; they may have hydroids and colonial ascidians on the free surface. The tunic is thick, cartilaginous, with numerous orange vessels (in live and preserved materials). The body is elongate, 2.5–5.0 cm (including the oral siphon) by 1.0– 1.7 cm, without the tunic; it retains an orange coloration two months after fixing in formalin but loses that color over longer time in preservation. Both siphons are 0.3–0.7 cm long; the oral siphon has 8–9 smooth lobes; the atrial siphon is displaced 1.0– 2.1 cm from the oral tentacles and has 6–7 smooth lobes, between which are orange spots.

On the right side the musculature comprises a thin net of fibers; on the left side the longitudinal fibers extend from the oral siphon and short fibers are perpendicular to the dorsal margin of the body. In the siphons, wide longitudinal muscles bands may be seen in relaxed animals.

The 59–101 oral tentacles are of four sizes, with the largest 1.6–4.5 mm long. The prepharyngeal groove is double, without projections; the distance between the prepharyngeal groove and the oral tentacles ring is 0.4–1.0 mm and within this region some animals may have papillae. The peritubercular area is small; the dorsal tubercle aperture is U-shaped and may or may not have enrolled ends. The neural ganglion is close to the dorsal tubercle. The dorsal lamina is smooth and double anteriorly, toothed and simple posteriorly; it passes by the esophageal aperture on the left and follows to the end of the pharynx (3.7–8.8 mm beyond the stomach); papillae are absent on the right side of the dorsal lamina. A narrow lamina is on the right side of the esophageal aperture. The pharynx is very pleated and has 34–42 longitudinal vessels on each side and 87–178 transverse vessels; 7–10 stigmata per mesh; primary papillae are simple or trilobed. Secondary papillae and parastigmatic vessels are absent.

The alimentary canal occupies about half of the left side of the body. The stomach is rounded, with 9–17 internal folds; the isodiametric intestine has both loops; the aperture of the anus is bilobed and opens 4.4–20.0 mm away from the ring of oral tentacles. Renal vesicles are 0.06–0.1 mm in diameter, cover the stomach and intestine and are more conspicuous on the side of the atrial cavity.

The ovary is cauliflower-shaped, located within the primary and secondary intestinal loops, visible both from the outside and from the atrial cavity side; oocytes are 0.1–0.15 mm in diameter. The testis follicles are elongated and overlay the stomach and most of the intestine. Gonoducts open just posterior to the anal aperture.

Remarks. In Panama, on the Atlantic side, another orange species, Ascidia corallicola sp. nov., also has lobes in the siphons with smooth margins and orange spots between the lobes, body musculature formed by a net, primary pharynx papillae trilobed, 8–11 internal folds in the stomach and ovary lobed. However, A. corallicola sp. nov. has ten lobes in the atrial siphon, well-developed body musculature, projections on the prepharyngeal groove, 5–7 stigmata per mesh, dilated rectum and ovary restricted to the primary intestinal loop. In the same region, Ascidia curvata is similar in the number of lobes in the siphons, body musculature pattern, and the shape of both the digestive tube and ovary. But A. curvata does not have bands of longitudinal muscle fibers on the siphons, the body musculature is organized in parallel fibers on the ventral margin, and there are only 5–7 stigmata per mesh, differing from A. bocatorensis sp. nov. In the Atlantic Ocean, A. tenue is very similar to A. curvata and can be distinguished from A. bocatorensis sp. nov. by the absence of muscular bands in the siphons, reduced number of stigmata per mesh (2–5), presence of papillae on the right side of the dorsal lamina and fewer folds in the stomach (6– 8).

Ascidia decepta Kott, 1985 and A. occidentalis Kott, 1985 , both described from the Pacific Ocean ( Australia and Tasmania), also have a net of fibers of muscles on the right side of the body and large number of stigmata per mesh ( Kott 1985). Ascidia decepta differs from A. bocatorensis sp. nov. because of the sand embedded in the tunic, absence of muscular longitudinal bands in the siphons and body musculature arranged as parallel fibers along the ventral margin ( Kott 1985). Presence of projections in the lobes of the siphons and reduced number of oral tentacles (about 30) ( Kott 1985) are the characteristics that distinguish A. occidentalis from A. bocatorensis sp. nov.

Figures

FIGURE 2. Ascidia bocatorensis sp. nov. A. Animal in the field. B. Right side of body (without tunic). C. Left side of body (without tunic). Scale bar: B, C = 1.0 cm.

FIGURE 3. Ascidia bocatorensis sp. nov. A. Right side of body (external), showing muscles. B. Left side of body (external), showing the gut and gonads. C. Gut and gonads (internal). Scale bar: A, B, C = 0.5 cm.