Pterygascidia kanakae, Monniot, 2021

Monniot, Francoise, 2021, New records of deep-sea ascidians (Tunicata, Ascidiacea) from the New Caledonia region, Zootaxa 4996 (3), pp. 443-468 : 450-452

Pterygascidia kanakae sp. nov.

Figures 8 , 9

Station: Kanadeep 12-742-03. One specimen (Holotype MNHN P1 .PTE 3 – slide A1. 1903) .

Very soft and transparent 23.5 cm long ( Fig. 8A ) the body has the general shape of the genus with the thorax and abdomen included in a single segment followed without a neat constriction by a wide and long peduncle.The anterior part of the body was a little damaged when collected, but most of the internal organs are preserved. The oral aperture opens at the base of the siphon developed into a hood which contains muscular fibres ( Fig. 8B , 9A ). The atrial aperture has eight round lobes above a few circular muscle fibres. No wing-shaped extensions of the tunic were seen associated with the atrial siphon, but the tunic is partly torn at this level.An average of 60 oral tentacles is distributed in two orders of size. The musculature is restricted to the thorax. The muscles are in transverse spaced fibres running from the endostyle to the middle of each body side and shorter transverse fibres are along the dorsal side. The dorsal tubercle opens in a slit. The dorsal lamina comprises pointed languets. The thin branchial tissue ( Fig. 8C ) extends to the posterior end of the body; about 50 longitudinal vessels were counted on the right side with a single stigma per mesh ( Fig. 8C ). The digestive loop is long and straight; it begins with a short oesophagus in continuity with an olive-shaped horizontal stomach sided by two round glandular masses ( Fig. 9C ). The state of the stomach wall does not allow seeing if it has ridges. The intestine ends in a smooth-edged anus ( Fig. 9B ) The gonad is totally different from those described for P. longa ( Van Name, 1918) . In the present specimen the gonad is hermaphrodite in a single organ, parallel to the intestine but not adherent to it ( Fig. 9C ). It begins in the bottom of the gut loop and extends parallel to the intestine up to the base of the atrial siphon. Several groups of testis vesicles( Fig. 9D ) are applied along the axis of the long tubular ovary. The sperm duct issuing from each group of testis lobes connects to a common sperm duct running along the length of the ovary ending in four genital papillae. In Pterygascidia kanakae sp.nov. male and female elements are associated in a single gland and represent a different organisation from the status described by several authors for Pterygascidia longa ( Van name 1918; Millar 1963; Tokioka 1971a, 1971b; Monniot & Monniot 2003 Figs 3A , 4B ; Kott 2008). In P. longa the testis vesicles are spread along a large part of the intestine wall, the common sperm duct emerges in the bottom of the gut loop to join the base of the tubular ovary and remains applied to the ovary passing the female papilla and ending in a single male papilla.

Kott (2008) established the synonymy of the genera Pterygascidia Sluiter, 1904 and Ciallusia Van Name, 1918 , a status generally accepted. Concerning the species, a doubt about the synonymy of P. mirabilis Sluiter, 1904 and P. longa remains, especially that of Tokioka (1971b) who re-examined Sluiter’s material, the descriptions of the tunic extensions are slightly different.

Figures

FIGURE 3. Pharyngodictyon sp., scale bar = 1cm.

FIGURE 8. Pterygascidia kanakae sp. nov. A, specimen; B oral siphon; scale bars = 1cm. C, part of the branchial tissue.

FIGURE 9. Pterygascidia kanakae sp. nov. A, anterior part of the body; B, anus and part of dorsal lamina; C, gut and gonads; D, testis lobes and sperm duct. Scale bars A and C = 1cm.

FIGURE. 4. Protoholozoa incrustans sp. nov. colony, scale bar = 1cm.