Eudistoma globosum Kott 1957

Eudistoma globosum Kott, 1957

Eudistoma globosum Kott 1957, p 72; Kott 1990a, p 210.

Distribution

Previously recorded (see Kott 1990a): Western Australia (Houtman’s Abrolhos, Cockburn Sound, Margaret River); Queensland (Capricorn Group). New records: Tasmanian Canyons (Ling Hole, 174 m).

Description

Colonies are about 3 cm high, simple, upright lobes with a short, thick, cylindrical stalk and a conical naked head. The long zooids, characteristic of the genus, open all around the head and extend crowded and parallel to one another down into the base of the stalk. Sand is crowded in the stalk and projects up into the centre of the lower half of the head.

Remarks

Zooids of species in the genus Eudistoma are very similar. The zooids all have short thoraces with numerous stigmata, characteristic long oesophageal necks with the stomach and gonads in the pole of the gut loop at the posterior end of the zooid and muscular body wall with an almost continuous outer coat of transverse fibres and inner longitudinal bands that continue into the abdomen. Because of this lack of diversity in the zooids, distinguishing characters are often more likely to be found in the colonies and the larvae.

The form of the small, simple, compact colonies of the present species and the distribution of sand in them is characteristic. The genus is not known from the sub-Antarctic south of New Zealand and the Tasmanian Canyons, and its original provenance may be from the tropics, where it is most diverse. However, the record from Margaret River and its occurrence south of Tasmania suggests that it is a temperate species which extends northwards on each side of the continent.