Molgula delicata Monniot C. & Monniot F. 1991

Exbodi, Françoise Monniot, 2022, Additional records of bathyal ascidians (Tunicata) from the New Caledonia region, Zootaxa 5195 (3), pp. 201-223 : 220-221

Molgula delicata Monniot C. & Monniot F. 1991

Figure 18

Station: SPANBIOS: DW 5176, 3 specimens.

The specimens, 4 to 5 cm in diameter, have a thin tunic heavily coated with sand and wearing thin and dense filaments resulting into a brittle shell. The ascidians were damaged during their collection. The siphon apertures are inconspicuous and close to each other ( Fig. 18B,C ). The body wall is thin and transparent ( Fig. 18A,B ). Longitudinal muscle ribbons starting from the apertures are short. They cross thinner circular fibres around the siphons ( Fig. 18A ). Between the siphons, in the middle of the dorsal side of the body wall, an additional long transverse muscle fibre extends to both sides ( Fig. 18B,C ). This peculiar muscle design was figured in Monniot C. & F. (1991, Fig. 34B). The oral tentacles are ramified but short. The prepharyngeal band is curved in a deep V ( Fig. 18C ). The branchial tissue is thin with six folds on each side with very deep infundibula. Some extra infundibula can be seen between the folds. The gut forms a long loop ( Fig. 18A ). The stomach has six longitudinal folds. The anus rim is smooth. There is one long sinuous gonad on each side ( Fig. 18A ); the ovary is tubular with testis vesicles on each side. The ducts issuing from the testis vesicles join at the surface of the ovary to form a single canal erect with several papillae along its length (as figured in Monniot C. & F. 1991 Fig. 34C). The oval kidney lies at some distance posteriorly from the right gonad ( Fig. 18A ).

Molgula delicata collected several times from New Caledonia between 500 and 800m depth (Monniot F. & Monniot C. 2003) is also present in New Zealand down to 1000m depth ( Sanamyan & Sanamyan, 1999) but has not been recorded elsewhere .

A copepod and an amphipod have been found inside the body.

Figures

FIGURE 18. Molgula delicata. A, body ventrally opened. B, dorsal side of the body wall. C, internal side of the neural region. Scale bars = 1cm