Microcosmus longicloa Monniot C. & Monniot F., 1991

Monniot, Francoise, 2021, New records of deep-sea ascidians (Tunicata, Ascidiacea) from the New Caledonia region, Zootaxa 4996 (3), pp. 443-468 : 456-457

Microcosmus longicloa Monniot C. & Monniot F., 1991

Figure 13

Stations: Kanacono DW 4727; DW 4728; DW 4781. Four specimens.

The bodies of the different specimens in this collection all have the same shape ( Fig. 13A ). The largest specimen is 7 cm in length. The siphons are well apart, the atrial one always longer ( Fig. 13 ). The tunic is rough and leathery but thin with spinules of 10µ on the siphonal lining ( Fig. 12D ). The muscle ribbons are evenly spaced and dense in a web on the body wall ( Fig. 13C ). There are about 60 thick ramified oral tentacles. The dorsal tubercle, C-shaped with horns rolled inward is placed in a deep V of the prepharyngeal band ( Fig. 13B ). The dorsal lamina has a plain edge. There are seven high folds on each side ( Fig. 13B ) and four to five longitudinal vessels between the folds. The digestive loop is ventral and only occupies a part of the left body side close to the endostyle ( Fig. 13C ). The digestive gland is in two parts: one anterior with lobes in lamellae and one posterior with thin finger-like papillae. The anus with eight lobes opens close to the oesophagus. There is one long gonad on each side. The left gonad crosses and covers the intestine the right gonad is also ventral ( Fig. 13C ). In all specimens two endocarps are placed anterior to the gonad on the right body side and one endocarp is above the gonad on the left body side, while additional endocarps cover the gonad lobes ( Fig. 13C ). There is an atrial velum but no papillae at the atrial aperture.

The newly collected specimens are similar in all characters to those described from the same region ( Monniot & Monniot 1991).

Figures

FIGURE 12. Polycarpa papillata. A, two specimens; B, specimen without tunic; C, body ventrally opened; D, branchial tissue. Scale bars = 1cm.

FIGURE 13. Microcosmus longicloa. A, one specimen; B, branchial sac; C, other specimen branchial sac removed; D, spinules. Scale bars = 1cm.