Sycozoa sp.

Sanamyan, K. E. & Sanamyan, N. P., 2002, Deep-water ascidians from the south-western Atlantic (RV Dmitry Mendeleev, cruise 43 and Academic Kurchatov, cruise 11), Journal of Natural History 36 (3), pp. 305-359 : 313-314

Sycozoa sp.

(®gure 5)

Material examined. St. 4100, 1265± 1376 m, more than 30 colonies.

Description. Most colonies are attached to the test of Corella eumyota Traustedt, 1882 . The colonies consist of small heads arising on long, thin, hard and usually unbranched stalks. Basally the stalk has numerous relatively thick rhizoids spread over the substratum. The heads of all colonies are in sheets (®gure 5A). The zooids are large, up to 9 mm long. The atrial aperture is large, the thoracic wall is seen only just below the branchial aperture and along the endostyle, but it may have been stripped oOE when zooids were removed from the tunic. There are no true stigmata. There are three transverse branchial vessels, connected to one another and to the anterior and posterior pharyngeal wall by long thin unciliated membraneous strips (®gure 5B). About 20 such modi®ed stigmata are in each half row. Parastigmatic vessels are not present. The abdomen is long and narrow, the smoothwalled stomach is in its distal third. Seven to ten large male follicles form a compact protruding mass beside the gut loop. The larval trunk is 0.4 mm in diameter and 0.8 mm long, and the tail makes two complete circles around it.

Remarks. Unfortunately all the colonies are much disintegrated; only few of them contain zooids, and it not possible to provide a complete description of this interesting species, which seems to be distinct from other known species of Sycozoa . The present specimens resemble some other species of Sycozoa , particularly the widely distributed S. sigillinoides Lesson, 1830 . Corresponding features are the shape of colony, long tail of the larva, large number of stigmata per row. In the present specimens, however, the stigmata appear to be non-ciliated and are very long, and such stigmata are not known in other species of this genus. The branchial sac resembles that of Distaplia megathorax Monniot and Monniot, 1982 , but the latter species has parastigmatic vessels and a relatively short oesophagus.

This is the ®rst record of the genus below 500 m.