Eudistoma eboreum Kott, 1990

Kott, Patricia, 2008, Ascidiacea (Tunicata) from deep waters of the continental shelf of Western Australia, Journal of Natural History 42 (15 - 16), pp. 1103-1217 : 1118

Eudistoma eboreum Kott, 1990

Eudistoma eboreum Kott 1990a, p. 205 .

Distribution

Previously recorded (see Kott 1990a): Queensland (Lizard I.). New record: Western Australia CSIRO SS10 / 05 (Kalbarri, Stn 102, 96– 98 m, 05.12.05, QM G328054 ) .

Although the species was formerly known from the north-eastern coast of the continent, the new record from the north-western coast suggests a tropical Indo- West Pacific range.

Description

The newly recorded colony is a firm, irregular mat, orange in preservative. The upper half of the colony is soft and cloudy with orange vesicles in the test. Zooids are withdrawn into the sandy basal half of the colony. Each zooid has a single, large embryo at varying levels of the abdomen, presumably having been fertilized at the base of a long abdomen, although in the present specimen the whole zooid is very contracted. Zooids are muscular, as is characteristic of this genus, with longitudinal bands and a continuous coat of transverse thoracic muscles.

Remarks

Apart from the apparent absence of rudimentary systems and the black pigment cells around the zooids, this specimen closely resembles Eudistoma eboreum Kott, 1990a (known previously from Lizard I.) and the Western Pacific tropical Eudistoma muscosum Kott, 1990a . In addition to the larger (0.04 mm) vesicles in the test, the latter species has shiny reddish spheres (0.01–0.02 mm) and dark coloured zooids that separate it from the present species. The present species has been assigned to the species E. eboreum on the basis of its sand-free test on the top half of the colony which is cloudy with large tan/orange/yellow vesicles. The specimens only lack the fusiform to dendritic cells found in E. eboreum . Only a single larva in each zooid has ever been recorded in this species, although the larval structure is not yet known. Eudistoma maculosum Kott, 1990 is a temperate species with dark coloured zooids.