Culeolus likae, Sanamyan & Sanamyan, 2002

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 : 347-350

Culeolus likae sp. n.

(®gures 26, 27)

Material examined. St. 916, 4664±5631 m, four specimens, one of which was damaged and was not dissected; st. 4109, 5225 m, one specimen. HOLOTYPE KIE 1/1038 (st. 916).

Description. All specimens have a similar appearance. In large specimens the body is nearly cylindrical and ¯attened laterally, with a somewhat enlarged posterior end; smaller specimens are oval or egg-shaped. The largest specimen (holotype) has the body 8 cm long and 5.5 cm high and the peduncle 85 cm long. The peduncle, 1.2 ±1.8 mm diameter, contains horny trabeculae and has a shallow groove running along its whole length. Basally it breaks into small tufts of delicate rhizoids, suggesting that the specimen was attached to a hard substratum.

The test is thin, soft and transparent, whitish or with faint yellow-brownish tint, body muscles and internal organs are rather indistinctly seen through it. The test is nearly smooth, it contains numerous small and uniform vesicles, each with a small dark granule inside, but in most places vesicles are embedded in the test and do not protrude above the surface. The postero-ventra l crest consists of three high lamellae arising on the most postero-ventra l point of the body and ending at one level halfway along the body. One of these lamellae, the highest, runs along the mid-ventral line and ends abruptly; the others curve along each side from the postero-ventral point of the body to become nearly parallel to the longitudinal axis, or their ends may turn slightly ventrally (®gure 26). Lateral lamellae end far from the atrial opening and their height gradually decreases toward the ends. There are no papillae or other ornamentation on the test.

The small atrial aperture, surrounded by a narrow band of slightly more rigid test, is on the postero-dorsal corner of the body. The branchial aperture is larger, on a short siphon and is widely open in the holotype.

The body wall is thin and transparent, with circular and radial muscles forming a rather regular network of large square meshes. The circular muscles are crowded around the siphons. The holotype has 20 large tentacles that protrude beyond the branchial ori®ce. They have three size orders, with relatively long primary, secondary and tertiary branches. The prepharyngeal band, consisting of two thick lamellae, runs close to the ring of tentacles and close to the branchial sac and makes a prominent dorsal V around the dorsal tubercle and neural ganglion; the latter is wholly anterior to the prepharyngeal band. The dorsal tubercle has an S-shaped opening. The branchial sac has the usual structure for Culeolus and has six folds on each side; the branchial formula for the holotype is: E8(6)5 (6)7 (7)7(9)6 (9)6 (8)- 5DL5(10)7 (10)6 (10)8 (7)6(5) 5(5)8E .

All specimens have three gonads on each side, the left and right gonads are placed symmetrically, parallel to the longitudinal axis of the body and directed towards the atrial ori®ce. On the left one gonad is in the gut loop, the second anterior to the pole of the gut loop and close to the endostyle, and the third is in the middle of the left side at the level of the pole of the gut loop. On the right, two gonads are on one line along the endostyle, and the third is dorsal to them. Each gonad consists of a compact globular mass of numerous, small male follicles over a short ovary, and a large ¯attened endocarp in which the gonad is embedded. Short male and female ducts arise under the globular mass of male follicles and open close to each other. The shape of the gonads may be diOEerent in diOEerent specimens. In the holotype the gonad in the gut loop is much smaller than the others; in the 65 mm specimen from the same station, the most posterior gonad on the right side is not present, but a corresponding endocarp is present. The specimen from st. 4109 (®gure 27B) has large, elongate gonads, but they not divided into lobes.

The gut loop is widely open, bunches of hepatic diverticula are present in two series along the sides of the stomach. The anus has two lobes with clearly smooth margins. A tubular heart is on the right side of the body along the endostyle. Spicules are abundant in the endostyle, heart and hepatic diverticula.

Remarks. This species is closely related and may even be identical with C. longipedunculatus Vinogradova, 1970 , known from three large specimens from the Kurile-Kamchatka Trench, north-west Paci®c. The common features are the shape of the crest, the long peduncle, reaching 132 cm in the 8 cm specimen, compact gonads, smooth anus and number of branchial folds. The main diOEerence is the number of gonads, C. longipedunculatus having two on each side. The number of gonads varies in some species of Culeolus and this is not a very reliable feature, especially when both species are known from such a small number of specimens. Nevertheless, we think it may be considered as valid, because all our specimens, even small ones with poorly developed gonads, have three gonads on each side, and all Vinogradova’s specimens have two. There are a few other diOEerences which, however, are less signi®cant. The peduncle of the north Paci®c species is much thinner, 0.5 mm in diameter along the whole length, the tunic is nearly translucent, spicules are not present in the internal organs. Absence of spicules cannot be explained by formalin ®xation, as Vinogradova (1970) suggested, because spicules are abundant in C. tenuis Vinogradova, 1970 , collected from the same station, and the specimens were ®xed together. However, presence or absence of spicules probabl y is not a very reliable feature.

We do not think that the specimen from the Indian Ocean, identi®ed doubtfully as Culeolus longipedunculatus by Monniot and Monniot (1985a), is conspeci®c with the present specimens. It has two gonads on the right, one on the left and the liver is diOEerent.

Culeolus recumbens Herdman, 1881 , has undivided gonads which, however, are diOEerent from those of the present species, and the test is densely covered by sand. Culeolus pinguis Monniot and Monniot, 1982 , from the Weddell Sea, has two bilobed gonads on each side and a diOEerent appearance, with the crest making a complete circle around the posterior end of the body. Other Antarctic species have long lobed gonads, and are not related to the present species. Culeolus suhmi: Monniot and Monniot, 1973 , has two compact gonads on each side and a diOEerent posterior crest. We have specimens of this species, and they clearly diOEer from C. likae (see description below).

Etymology. The species is named after Lika Kimberg, school friend of the ®rst author.