Corynascidia lambertae Sanamyan & Sanamyan 2002, sp.n.

Corynascidia lambertae sp.n.

(®gure 17)

Material examined. St. 4100, 1265± 1376 m, one specimen. HOLOTYPE KIE 1/1033.

Description. The body is 4 cm long and 1.5 cm wide in the anterior part, gradually tapering to the peduncle, which is 2 cm long and 5 mm wide. The specimen probably was attached to a stone, the base of the peduncle is ¯attened, spread out into a thin membrane without any root-like outgrowths. The test on the body is thin, naked, transparent and soft, but a little more rigid on the peduncle. Large apertures are on short diverging and obscurely lobed terminal siphons on the top of the body, one on each side of the upper surface (®gure 17B, C).

Thin circular muscles are present only around the margins of the siphons. A set of thin longitudinal muscles is on the upper third of the body and a series of short, parallel transverse muscle bands is below the branchial siphon. Muscles are thicker and more numerous on the right side of the body. Longitudinal muscles anterior and posterior to the atrial siphon form two thick bundles crossing the mid-dorsal line. None of the other muscles cross the mid-line of the body.

About 80 tentacles of at least three size orders arise from a low muscular velum. The tentacular circle is near the edge of the siphon ventrally, but far from it dorsally. In full expansion the branchial siphon apparently is directed downward, as in C. herdmani (see Sanamyan, 1998, ®gure 4). The prominent dorsal tubercle has an oval longitudinal opening. The prepharyngeal band is composed of two lamellae which are equal along most of their length. The anterior lamella curves only slightly around the dorsal tubercle, but the posterior lamella makes a short narrow, thick-walled V behind the dorsal tubercle. An elongated neural ganglion is hidden under the dorsal V. The dorsal lamina has a line of short languets. The endostyle is long, extending from the branchial siphon forming an angle in the top of the peduncle and continuing a little upwards. The body wall and the branchial sac project slightly into the top of the peduncle. Transverse vessels are directed obliquely to the longitudinal axis of the body and are of two regularly alternating orders. The stigmata are in about 45 transverse rows of 37±40 square meshes with no more than 1.5 irregular spirals. The membrane of the pharyngeal wall between the perforations is very much reduced and thread-like (®gure 17D). The spirals are crossed by two thin radial vessels. About 50 longitudinal vessels are present on each side of the branchial sac, they are seldom interrupted and are on long papillae arising from the transverse vessels.

The gut loop is U-shaped, straight, narrow and vertical. The stomach is clearly demarcated from the oesophagus and intestine and has well-developed but slightly irregular external longitudinal folds. The long straight rectum lies directly under the dorsal lamina. The stomach and ascending limb of the intestine, which is relatively long, are slightly displaced to the right of the mid-line. The form of the anal border was not determined.

The gonads are immature. The small ovary with few oocytes, and small separated testicular follicles are in the gut loop.

Remarks. This is the fourth pedunculate Corynascidia, the other three being C. suhmi Herdman, 1882, C. herdmani Ritter, 1913 and C. hartmeyeri Monniot and Monniot, 1994. Corynascidia suhmi and C. hartmeyeri diOEer from the present species in many characters, including the position of the siphons, shape and orientation of the gut loop, and shape of the stigmata with their more numerous coils and especially numerous radial vessels. Corynascidia hartmeyeri has two lines of dorsal languets. The present species seems to be more closely related to C. herdmani from the Bering Sea, recently rediscovered by Sanamyan (1998). It has a similar body form, similar position and shape of the siphons and similar shape of the gut loop with folded stomach. It has a diOEerent branchial sac which Sanamyan (1998) did not ®gure as it is similar to that ®gured by Ritter (1913) in the original description. In C. herdmani the stigmata are better developed than in C. lambertae and coiled up to four times, and transverse muscles are not present posterior to the branchial siphon.

Etymology. The species is named after Dr Gretchen Lambert.