Cystodytes

Monniot, Françoise, 2009, Some ascidians from Indonesian marine lakes (Raja Ampat Islands, West Papua), Zootaxa 2106, pp. 13-40 : 25-26

Cystodytes sp.

( Fig. 10 )

? Cystodytes multipapillatus Monniot F. 1988: 220, fig. 10 C,E, New Caledonia; Monniot F. & C. 2008: 836 pl. 5C, New Guinea.

Material. Indonesia. West Papua, Gam Island, Danau Nine Gam marine lake, 00°26.970’S – 130°29.149’E, 0.5–2m, 04/XI/2007, coll L.J. Bell and L.E. Martin, DNG 0 83 ( MNHN A3 CYS 135).

The 3 colonies are in crusts of several cm large and no more than 3mm thick ( Fig. 10 A). The colour in life is dark purple and remains in formalin. The tunic is opaque and does not let see the white zooids. No trace of spicules could be found in the colonies, no polarizing particules, and no more ghost shapes of spicules in the tunic indicating a possible dissolution.

The zooids are in circular systems, the atrial siphons opening separately in a ring at the smooth and flat colony surface. The zooids ( Fig. 10 B) 2mm long have the common shape of the genus. There are 6 oral lobes.

The testis is composed of a rosette of numerous elongated lobes placed at the posterior end of the abdomen. One embryo is incubated in a protruding dilatation of the body wall at the base of the thorax ( Fig. 10 B). Colourless mature larvae where found isolated from the zooids ( Fig. 10 C). Their trunk 1.1mm in length has 4 stigmatal rows. The adhesive papillae are variable in number: 3 papillae in a line, in the centre of a circular ring, or 1 to 2 additional papillae intercalated.

Species in the genus Cystodytes are mainly distinguished by their spicules and larvae. Consequently an identification at the species level would be hazardous here because of the lack of spicules. However, many similarities with C. multipapillatus exist, except that the latter has a deeply pigmented larva with many more adhesive papillae, dense calcareous spicules encapsulating the zooids and a variable number of oral lobes: 6 to 8.

The species from Raja Ampat was collected on mangrove roots in a marine lake subjected to a variable salinity. This may explain the absence of calcareous spicules. The variable number of adhesive papillae may also be due to unfavourable ecological conditions.

Figures

FIGURE 10. Cystodytes sp.: A, colony; B, zooid; C, larva. Scale bars: A = 0.5 mm; B = 0.25 mm. B, C, stained with hemalum.