Corella eumyota Traustedt, 1882

Turon, Xavier, Cañete, Juan I., Sellanes, Javier, Rocha, Rosana M. & López-Legentil, Susanna, 2016, Ascidian fauna (Tunicata, Ascidiacea) of subantarctic and temperate regions of Chile, Zootaxa 4093 (2), pp. 151-180 : 165

Corella eumyota Traustedt, 1882

Fig. 7 B–D

References and synonymy: Corella eumyota Traustedt (1882) p. 273; Monniot (2013) p. 138.

Localities: 2N, 3N, 6N, 8N.

The specimens measure up to 3 cm in total length and are fixed ventrally or slightly tilted over the right side. The tunic is translucent and the mantle can be from whitish to orange. There are 7–8 red pigmented spots in the oral siphon and 4–6 in the atrial siphon.

The musculature of the mantle is well developed on the right hand side, where the fibres form a crisscrossed network dorsally and have a more transverse orientation ventrally. There are many simple tentacles (up to 100 of different sizes). The neural gland has a “U” shaped aperture. The branchial sac is typical, with over 30 longitudinally arranged vessels and coiled stigmata below them. Slender dorsal languets mark the dorsal midline of the branchial sac.

The digestive, as is characteristic of this genus, lies on the right hand side. The stomach is folded (folds are better seen from the external side), and the intestine forms a wide loop occupying up to 3/4 of the right side of the mantle. The final part of the intestine runs adjacent to the dorsal languets and ends in an anus with minute lobes. The interior part of the digestive loop is occupied by the gonads, forming a compact mass of tissue. The genital apertures are inconspicuous (usually staining is required to observe them), on the inner side of the gonad mass, and consist of a narrow slit for the male papilla, and a wider aperture for the female gonad.

Remarks. Lambert (2004) was the first to note the particular shape and position of the genital ducts in Corella eumyota , and this character clearly separates this species from other congeners (Alurralde et al. 2013). C. eumyota was considered until recently the only species of the genus in the southern hemisphere, but Alurralde et al. (2013) and Monniot (2013) showed that there are at least three species. Previous reports of C. eumyota should therefore be taken with caution. The Chilean populations should retain the original name of C. eumyota , described from Chile (Valparaiso), and recently introduced into the northern hemisphere (Lambert 2004).

Figures

FIGURE 7. A, Ciona robusta on a buoy, note also some Asterocarpa humilis (orange-coloured). Corella eumyota. B, whole individual; C, dissected individual; D, right side of the mantle, branchial sac eliminated. Inset shows magnification of the zone of the genital openings. The specimen in C and D has been stained. Scale bars: A, 10 cm, B, 2 mm, C, D, 1 mm.