Polycarpa spongiabilis (Traustedt, 1883)

Fig. 15

Traustedt 1883, West Indies and Brazil.

Van der Sloot 1969, Carribean Sea and synonymy; Rocha et al. 2005 Panama. Stations: AB 102; AB 143; AD 208; AD 229; AD 230; AM 26; AR 51; AR 87; AR 103; AR 107; AR 164; AR 180; AR 367. (MNHN S1 POL.B 584)

P. spongiabilis is a common ascidian of the Caribbean Sea and specimens from Madibenthos agree with the precise description given by Van der Sloot (1969) so only the main specific characters are given below. The specimen size varies from 1cm to 8cm. The tunic is thick but soft either covered with epibionts or sand and shells. The body wall is brownish in formalin with a dense musculature but the polycarps remain slightly visible from outside. The oral tentacles are numerous in 3 orders of size with brown pigment. There is a large oral velum (Fig. 15A,B) and a cloacal velum with an undulated edge wearing thread like papillae as figured in Van der Sloot (1969 fig. 63) and Monniot C. (1983 fig. 9B). The dorsal tubercle with more or less curved horns is located in a wide V of the prepharyngeal area devoid of papillae. The branchial sac is characteristic of the species (Fig. 15 A’, B’). There are 4 folds on each side, though in large individuals two or more longitudinal vessels just to the right of the dorsal lamina join posteriorly to make a partial 5th branchial fold (Fig. 15 A’, B’). The alimentary canal forms a closed loop situated posteriorly on the left body side. There is a small curved stomacal caecum (Fig; 15A). The anus has more or less low lobes. The primary gut loop contains one large foliated endocarp and two smaller ones (Fig. 15). The polycarps are oval and partly included into the body wall (Fig. 15A,B); sometimes they occupy the whole surface of the internal body wall. There are no endocarps at all on the body wall except those inside the gut loop. The geographic distribution of P. spongiabilis is restricted to the Caribbean Sea, Florida (Van Name 1945), Bermuda (Monniot C. 1972), Brazil (Rocha et al 2012).