Culeolus suhmi Herdman, 1881

Sanamyan, K. E. & Sanamyan, N. P., 2006, Deep-water ascidians (Tunicata: Ascidiacea) from the northern and western Pacific, Journal of Natural History 40 (5 - 6), pp. 307-344 : 331-333

Culeolus suhmi Herdman, 1881

( Figure 13 )

Culeolus suhmi Herdman 1881, p 86 ; Sanamyan and Sanamyan, 2002, p 350 (synonymy); 2005, p 15.

Culeolus ushakoυi Redikorzev 1941, p 183.

Culeolus murrayi: Vinogradova 1970, p 498 .

? Culeolus murrayi Herdman 1881, p 83 ; 1882, p 91; Monniot and Monniot 1982, p 117.

Material examined

St. 5621, 5035– 5220 m, nine specimens (identified by Vinogradova 1970 as C. murrayi ); St. 6143, 4820 m, two specimens.

Description

The specimens from St. 5621 are too mutilated and the description is based on a 24 mm long specimen from St. 6143 ( Figure 13 ). The surface is covered by crowded small, hemispherical or sometimes pointed vesicles, many of which have opaque granulae inside. A complete ring of long crowded papillae encircles the posterior end of the body with the atrial aperture in the centre of this ring. The ventral papillae are noticeably longer than on the sides of the body and they are covered by the same minute warts as on the remainder of the test. Similar large papillae are in short transverse rows running from each corner of the branchial aperture to the base of the peduncle at the antero-ventral point of the body. A few separate and relatively long papillae are on the mid-ventral line, but they do not form a distinct mid-ventral crest.

The body wall is thick and opaque. The radial and circular muscles form a regular meshwork as in C. tenuis but muscle bands appear to be much thicker. The tentacles are few and not much branched: the longest dorsal tentacles have only few short, sparse, primary branches, while the smaller branchial tentacles may be simple (not branching). The specimen has two gonads on each side. On the right the anterior gonad is composed of three large lobes, the posterior gonad is shorter and not divided. On the left, one gonad is in the gut loop and has two masses of male follicles covered by a single large endocarp, and another small undivided gonad is outside the loop, halfway along its descending limb, close to the intestine. The anal margin has about 10 distinct lobes. Spicules are present in all organs.

Remarks

The specimen described above, from the northeast Pacific, is identical with the specimens from the Kurile-Kamchatka Trench identified by Vinogradova (1970) as C. murrayi . Vinogradova did not describe their internal structure, concentrating instead on a detailed description of the external appearance, relative length of the body and its peduncle, and variations in the shape of the dorsal tubercle. It is clear that her identification is based mainly on the external resemblance of her specimens and the specimen of C. murrayi figured by Herdman (1882): the specimens have similar body shape, papillated test, and a complete ring of crowded papillae encircling the posterior end of the body. All these features are also characteristic for the north Atlantic specimens of C. suhmi we had the opportunity to examine ( Sanamyan and Sanamyan 2005). The north Atlantic specimens of C. suhmi have exactly the same branched papillae on the mid-ventral crest as the north Pacific specimens, although this feature was previously regarded as a species-specific feature for C. murrayi .

A small part of the material identified by Vinogradova as C. murrayi (nine specimens from St. 5621, see Vinogradova 1970, Figures 5 , 6 ) was placed at our disposal. Most of these specimens, including a group of several specimens she figured ( Vinogradova 1970, Figure 6 ) are mutilated (by lateral or dorsal dissections without removing the test), in the extent that even the number of gonads was obscured. The single intact medium-sized specimen was, however, in perfect condition. It has two gonads on each side, the right ones consisting of three and five large lobes, respectively; on the left, one gonad is inside and the other outside the gut loop and both have five lobes. We failed to find any reliable feature distinguishing this specimen from C. suhmi and all specimens of C. murrayi of Vinogradova (1970) are here considered conspecific with C. suhmi .

Culeolus ushakoυi also apparently is conspecific with C. suhmi . According to Redikorzev (1941), it has a complete ring of papillae around the posterior end of the body and two gonads on each side, anterior ones with three lobes and the posterior ones with two lobes.

The type specimen of C. murrayi has three short gonads on each side ( Monniot and Monniot 1982), while the present specimens (as well as C. ushakoυi), have two. Although some specimens of C. suhmi also may have three gonads on the right side, their position appears to be different from the gonad in C. murrayi and at this stage the species do not appear to be conspecific.

Culeolus robustus Vinogradova, 1970 is also similar to C. suhmi . There are 15 known specimens (all from the Kurile-Kamchatka Trench, St. 5608). It is not clear which features were used by Vinogradova to distinguish her species from other Culeolus species. We dissected the intact paratype of this species ( Figure 14 ). It has two gonads on each side, the anterior one having two lobes, the posterior one being entire. One gonad on the left is inside, the other is outside the gut loop. Internally this specimen is indistinguishable from the specimen of C. suhmi described above (compare Figures 13B and 14B ). The body of C. robustus is slightly more elongated than in C. suhmi . The only apparent difference is the shape of the postero-ventral crest, closed in C. suhmi and opened dorsally in C. robustus . In the larger specimens of C. robustus the papillae are more or less united into a thick membrane, while they are separate in the smaller specimens. At this stage, the shape of the postero-ventral crest separates the species. Although this probably is a stable feature in many Culeolus spp., it could vary in others. Culeolus anonymus is another species similar to C. suhmi but with the crest open dorsally ( Sanamyan and Sanamyan 2002). The present material from St. 6143 contains two specimens very similar to the above-described C. suhmi , but with the postero-ventral crest opened dorsally. One of these specimens has two short gonads on the left and no gonads on the right; the other specimen has one gonad on each side in the gut loop. We are not sure if these specimens may be considered as abnormal specimens of C. suhmi or belong to another species.

Figures

Figure 5. Styela multitentaculata sp. nov. (A) Specimen opened along ventral mid line; branchial sac removed; (B) proximal part of the right gonad, external view through the transparent body wall (male follicles and the proximal end of the ovary); (C) part of the dorsal lamina; (D) internal view of the dorsal area (branchial and atrial tentacles, prepharyngeal groove, dorsal tubercle, and ganglion).

Figure 6. Styela sigma Hartmeyer, 1906. (A) External view; (B) specimen opened along ventral mid line; branchial sac removed.

Figure 13. Culeolus suhmi Herdman, 1881. (A) Intact specimen (whole stalk not shown); (B) specimen opened along ventral mid line; branchial sac removed to show gut, gonads, and muscles.

Figure 14. Culeolus robustus Vinogradova, 1970. (A) Intact specimen (whole stalk not shown); (B) specimen opened along ventral mid line; branchial sac removed to show gut, gonads, and muscles.