Eudistoma anaematum Kott, 1990

Kott, Patricia, 2006, Observations on non-didemnid ascidians from Australian waters (1), Journal of Natural History 40 (3 - 4), pp. 169-234 : 190

Eudistoma anaematum Kott, 1990

( Figure 2G )

Eudistoma anaematum Kott 1990a, p 196 .

Distribution

Previously recorded (see Kott 1990a): Queensland (Great Barrier Reef). New record: Queensland (Bowden Reef, AIMS 17693).

Description

The newly recorded colony has firm gelatinous test containing the usual long polycitorid zooids, which are arranged in circles with the long atrial siphons opening in the centre of the circle. Sand is not present either in or on the colony. The living colony was transparent and bluish beige. Dark, spherical pigment particles are scattered sparsely through the test of the preserved specimen. Zooids are robust, as previously described, with up to 30 stigmata in each of three rows and there is a long prestigmatal unperforated area in the pharynx. The almost spherical stomach is at the end of the long oesophageal neck, at the posterior end of the body. Zooids have up to two embryos developing in the atrial cavity. Larvae are similar to, although the trunk (0.75 mm long) is about half the length of the larval trunk of, E. globosum . The three antero-median adhesive organs have wide platforms of adhesive cells on short thick stalks, each surrounded by a shallow epidermal cup; and three narrow, median, ectodermal ampullae alternate with the adhesive organs. A large oval yolk mass almost completely occupies the larval trunk. The tail winds about halfway around the trunk.

Remarks

The species is distinguished from others in this homogenous genus by its naked, sand-free, translucent colony. Its larva is described here for the first time.

Figures

Figure 2. (A–C) Sigillina exigua sp. nov. (SAM E3300, syntype): (A) colony; (B) zooid; (C) larva. (D–F) Eucoelium orientalis: (D, E) colonies; (F) vertical section through colony showing position of sub-surface spicule layer. (G) Eudistoma anaematum (AIMS 17693): larva. Scale bars: 1 mm (A); 0.2 mm (B, C); 1 cm (D–F); 0.1 mm (G).