Protoholozoa pedunculata Kott, 1969

Maggioni, Tamara, Rimondino, Clara, Taverna, Anabela, Reyna, Paola, Lagger, Cristian, Alurralde, Gastón, Calcagno, Emilia & Tatián, Marcos, 2022, Abyssal ascidians (Chordata, Tunicata) from the Weddell Sea, Antarctica, including a new Styela species and stomach content identifications, Zootaxa 5093 (3), pp. 296-314 : 299-300

Protoholozoa pedunculata Kott, 1969

Figure 2

Protoholozoa pedunculata Kott 1969: 35 , figs. 17–20; Monniot C. & Monniot F. 1983: 36, pl. 5A and synonymy; Sanamyan K. & Sanamyan N. 2002: 315, figs. 6A-C; Tatián et al. 2005: 209; Monniot F. & Tatián 2020: 262, figs. 1–4.

Material examined: 61°45’S, 47°7’W, station 16, 1180 m, 20 March 2005, one specimen; 61°48’S, 47°28’W, 2000 m, 20 March 2005, three specimens.

Description. All colonies have a transparent tunic, free of epibionts or encrusted external material. Both, head and peduncle of the smallest specimen measure two cm in height. The remaining three specimens present heads that measure on average five cm and peduncles of 8.5 to 11.1 cm.

Zooids are arranged in oblique rows at the lateral sides of the heads. On average, zooids are 12 mm in length. Thorax and abdomen have the same length. The oral and atrial siphons have six weakly marked lobes. The dorsal tubercle is rounded. It is partially covered by a thick, circular and undulated pre-pharyngeal band. There are, on average, 14 oral tentacles. These become thicker and longer toward the dorsal side. There are two transverse vessels connected to each other by a short longitudinal vessel on each side of the body. In the zone of union with the mantle, each transverse vessel develops a prominent triangular languet.

In contrast with the description of the type material, the musculature of the zooids extends down to the level of the stomach. The vascular appendix is long and thin. The abdomen has 12 folds. The gonads are in the abdomen, inside the gut-loop. The sperm duct runs parallel to the rectum. No larvae were observed.

Remarks. Despite being a frequent species in Antarctic and Sub-antarctic areas, this is the first record of Protoholozoa pedunculata in the Weddell Sea.

There are only five species included in the genus Protholozoa, being P. pedunculata the most frequently reported species. The number of transverse vessels has been proposed to distinguish among species of the genus (Sanamyan K. & Sanamyan N. 2002): P. pedunculata and P. anthos Monniot C. & Monniot F., 1991 have two; P. pigra Monniot F., 1974 and P. incrustans Monniot F., 2021 have three; P. australiensis Kott, 1992 has four.

Figures

FIGURE 2. Protoholozoa pedunculata.