Culeolus herdmani Sluiter, 1904

Monniot, Francoise, 2021, New records of deep-sea ascidians (Tunicata, Ascidiacea) from the New Caledonia region, Zootaxa 4996 (3), pp. 443-468 : 461-463

Culeolus herdmani Sluiter, 1904

Figure 19

Stations: Kanacono CP 4739; DW 4717. Four specimens.

All characters already detailed in Monniot & Monniot (1991) are found again here for this species. The tunic on the head is naked though sometimes with a few epibionts but the long peduncle is encrusted with sand ( Fig. 19A ). The tunic is cartilaginous, thick but flexible with a row of papillae widely encircling the top of the body behind the atrial aperture. These papillae are reduced or missing in several specimens. The body wall is thin but with strong muscular fibres in a peculiar design ( Fig. 19C ). In addition to the siphonal sphincters a few longitudinal well spaced fibres extend from the siphons and rapidly curve to become parallel to the transverse circular muscles. On each body side one longitudinal muscular band is thicker, starts from the corner of the atrial aperture and crosses the body wall in a straight diagonal line ( Fig.19C ). About 14 oral tentacles have few but long simple digitations. One of these tentacles is often much longer than the others. The neural button-like tubercle is placed in a wide V of the prepharyngeal band. The dorsal lamina is made of tight pointed languets. The branchial tissue is thin with few longitudinal vessels arranged in 4 low folds per side. In a medium size specimen the formula is from the right to the left:

E - 1(2) 2 (2) 1 (4) 1 (3) DL (2) 1 (3) 1 (3) 1 (3) E.

The digestive loop occupies almost the entire length of the left ventral body side ( Fig. 19B, C ). The stomach is not neatly delimited and carries at its beginning a digitised hepatic gland, several smaller elements in a line fol- low. The first limb of the intestine is parallel to the endostyle and curves in a second limb which terminally turns up to open by two anal lobes. There are two gonads on the posterior part of the right body side ( Fig. 19B ) (three in one specimen) and two gonads inside the gut loop made of successive lobes. Each gonad is elongated with several protruding lobes along the tubular ovary. The testis vesicles form successive masses sometimes well spaced ( Fig. 19D ) the sperm ducts join in a common duct running along the ovary. In some places finger-like papillae are erect on the internal side of the gonads and contain a ramification of the common sperm duct ( Fig. 19D ). This uncommon structure was already mentioned for Caledonian specimens ( Monniot & Monniot 1991). This is not seen in all specimens and seems related to the gonad maturation. At each gonad extremity the oviduct and the common sperm duct end in divergent tubular papillae.

A very long vesicular endocarp is situated on the anterior side of the right body wall, a smaller endocarp is at the top of the gut loop. There are no other endocarps on the body wall. These endocarps are similar to those present in Culeolus recumbens Herdman, 1882 but all other anatomical characters are different in both species. No spicules were detected in the tissues.

Culeolus herdmani is widely distributed and abundant in the Pacific Ocean but not as deep as other Culeolus species , being more common only between 300 and 500 m depth.

Figures

FIGURE 19. Culeolus herdmani. A, two specimens; B, specimen ventrally opened; C, other specimen ventrally opened; D, gut and gonads. Scale bars = 1cm.