Distaplia florida Kott, 1990

Kott, Patricia, 2006, Observations on non-didemnid ascidians from Australian waters (1), Journal of Natural History 40 (3 - 4), pp. 169-234 : 186-187

Distaplia florida Kott, 1990

( Figure 8G )

Distaplia florida Kott 1990a, p 118 .

Distribution

Previously recorded (see Kott 1990a): South Australia (Great Australian Bight); Victoria (King I.); New South Wales ( Byron Bay ). New records: Victoria ( Flinders Pier , QM G308566 ) ; Tasmania ( Tasman Peninsula , 15–18 m, SAM E3293 ; Port Davey , 6–8 m, SAM E3233 ) .

Description

Colonies are soft, hemispherical or cushion-shaped (up to 3 cm diameter) to flat encrusting sheets with circular to elongate systems of zooids around large circular common cloacal apertures, about 5 mm apart. They are beige in preservative, and minute crystalline particles in the test give it a cloudy appearance. In the preserved specimens, radial furrows around the common cloacal apertures may be the result of preservation and/or contraction. A shallow concavity in the surface over each circular common cloacal cavity has its margin overhung by the surrounding surface test. Branchial apertures open beneath this overhang. The atrial apertures are large sessile openings around the common cloacal cavity with their anterior lips extending out into the margin of the common cloacal aperture. Black faecal pellets in the base of the circular common cloacal cavities are conspicuous from the surface. About 10 zooids surround each common cloacal cavity.

Zooids have a long oesophageal neck, a smooth stomach wall and gonads in the gut loop. Four rows of about 25 stigmata are each crossed by a parastigmatic vessel. A vegetative stolon projects into the base of the colony.

Remarks

Species of Distaplia are difficult to distinguish from one another, often having circular systems and soft cloudy test like the present one. The presence or absence of a posterior abdomen is a useful character but, when zooids are immature as in the present case, the smooth stomach wall helps to distinguish this species from others in which it is folded. The concavities over each common cloacal cavity in the preserved specimens appear to be characteristic of this species, although both species have circular systems, smooth stomachs and gonads in the gut loop. The present species is distinguished from Distaplia viridis Kott, 1957 by the more numerous branchial stigmata, and by its colour.

Figures

Figure 8. In situ images of: (A) Pseudodiazona claviformis (SAM E3280); (B) Pycnoclavella tabella (SAM E3290); (C) Stomozoa australiensis (SAM E3285); (D) Sigillina exigua (SAM E3300, syntype); (E) Distaplia australiensis (SAM E3294); (F) Distaplia australiensis (SAM E3295); (G) Distaplia florida (SAM E3293); (H) Distaplia pallida (SAM E3273).