Pseudodistoma fragile Tokioka, 1958

Monniot, Françoise, 2010, Some new data on tropical western Pacific Ascidians, Zootaxa 2561 (1), pp. 1-29 : 2

Pseudodistoma fragile Tokioka, 1958

( Figure 1)

Pseudodistoma fragile Tokioka, 1958: 316 Fig.3. Monniot F. 1987: 508 Fig 5. Monniot F. & Monniot C. 2001: 226 Fig. 19, 114E and synonymy.

Material. Viet Nam, coll. N.J. Pilcher et al., Con Dao Isl. , Bai Canh Isl. Bai Giong, 08°40.55’N – 106°41.16’E, 8m, 25/VII/2008, 0PHG 1653-G ( MNHN A1 PSE 77 ); Con Dao Isl., Bai Canh Isl., Quam Café, 08°40.01’N – 106°40.02’E, 8m, 25/VII/2008, 0PHG 1653-G ( MNHN A1 PSE 78 ) .

When fixed the colonies are totally disorganised remaining in mucous sheets and isolated zooids. The zooids are colourless and transparent with a wide square thorax ( Fig. 1). The oral siphon is short, the cloacal siphon tubular. The first row of stigmata is dorsally curved, with about 35 openings per side. A brood pouch is appended to the dorsal and posterior angle of the thorax ( Fig. 1). It contains one well developed larva at a time and a young embryo. The thoracic musculature is weak with few spaced longitudinal fibres. The abdomen is narrow, smaller than the thorax with the stomach at mid-length. The length of the post-abdomen varies but is always longer than the thorax plus abdomen; the testis vesicles are grouped in a cluster at the posterior extremity. The larvae 1.6mm long are as previously described (Monniot & Monniot 2001 Fig. 19) with 3 adhesive papillae and 4 ampullae on each side.

The geographic distribution covers the Pacific Ocean from Japan to Viet Nam but P. fragile is also recorded from Mozambique.