Culeolus recumbens Herdman, 1881

Monniot, Françoise & López-Legentil, Susanna, 2017, Deep-sea ascidians from Papua New Guinea, Zootaxa 4276 (4), pp. 529-538 : 536

Culeolus recumbens Herdman, 1881

Herdman, 1881

Herdman, 1882

Monniot C & Monniot F, 1982, Antarctic; 1991, New Caledonia Figs. 31D–33 A, B Monniot F & Monniot C, 2003 Figs. 34–49 B Sanamyan K & Sanamyan N, 1999, Tasman Sea Station CP 4435, 1 specimen (MNHN S2 CUL 60) GenBank Accession Number : KY882284

The body measures 2 cm in length and is attached to the substratum by a thin peduncle with a tuft of rhizoids measuring 10.5 cm. The peduncle is not sclerified but has sediment and foraminifers attached to it. The body tunic is soft and thin with a characteristic ring of triangular papillae at some distance around the atrial aperture ( Fig. 5 A). Some sand is present only on the oral siphon and at the twisted beginning of the peduncle. The body musculature is made of sphincters around the siphon apertures and of strong, spaced ribbons along the body ( Fig. 5 B). One of these muscles originates from the atrial siphon, is thicker than the rest and crosses each body side through the middle. The oral tentacles are long with few primary ramifications. The prepharyngeal band is slightly bent dorsally to enclose the dorsal tubercle, which opens into a simple hole. The neural ganglion is at mid-distance between the siphons. The branchial sac is damaged and eviscerated through the atrial aperture, with about 14 to 15 longitudinal vessels on each side making no distinct folds. The branchial meshes are large, square and without ciliae. The dorsal languets have a sharp tip. The gut ( Fig. 5 C) forms an open loop with a long narrow stomach covered with several successive hepatic lobes. The anus is fringed with numerous lobes. Two round gonads are located near the cloacal aperture on the right side and only one gonad is set within the gut loop. There is a long endocarp parallel to the endostyle on the right body side and a small vesicle at the top of the gut loop ( Fig. 5 C). No spicules were observed.

C. recumbens differs from all other species in the genus by having a peduncle that is not sclerified, few round gonads and endocarps. C. recumbens was known to be widely distributed in the southern regions of the Indian and Pacific oceans and its distribution now includes the equatorial waters around Papua New Guinea.

Figures

FIGURE 5. Culeolus recumbens. A, body with tunic, B, same than A without the tunic. C, body opened along the ventral line, branchial sac removed, stained with Masson’s haemalum. Scale bars: A: 1 cm; C: 5 mm.